When Facebook raised $240 million from Microsoft in 2007, and another $235 million in debt and equity in 2008, everyone thought they had plenty of cash to get through their big growth phase. With that kind of cash, the company could hire as many people as it needed to and not worry about profitability or going public or putting themselves available for an acquisition.

Facebook’s CFO, Gideon Yu, was fired this week. Facebook justified it by saying, “We have retained Spencer Stuart to lead our search for a new CFO and will be looking for someone with public company experience.” Weird, quite weird actually, because Yu is considered something of a Silicon Valley rock star for his help in selling YouTube to Google, experience with maybe the biggest VC firm Sequoia Capital, and oh, the position of Senior Vice President of Finance at Yahoo – very much a public company.

When things don’t seem right on this planet, they usually aren’t.

Less than two years ago Facebook CEO Mark Zuckerberg told the Wall Street Journal, “I consider it kind of a coup that we were able to recruit him (Yu) here…He’s just excellent.”

There’s no doubt that Facebook is growing at a breathtaking pace. A year ago, according to Comscore, they had just 74 million unique monthly visitors and 35 billion page views. Today those numbers have grown by 118% and 74%, respectively, to 161 million unique visitors and 61 billion page views per month.

There are, by Facebook’s account, ~200 million people using Facebook. For whatever reason, that number is probably much lower than the truth. By some estimates the number is more like 250M and as high as 300M. Why would an internet site downplay usage statistics? That is unheard of, and counter logical, in an advertising driven business vehicle. Maybe Facebook doesn’t want to expose their mounting financial tension?

The company is likely spending well over a $1 million per month on electricity alone. Bandwidth is likely another $500,000 or more per month on top of that. The company has earmarked $100 million to buy 50,000 servers this year and next. To keep up with the obscene growth and new user content, they must be constantly buying more storage systems. At up to $2 million each, that adds up quickly. Throw another $15 million per year in office and datacenter rent payments. And with 750 employees and growing, Facebook is spending at least another $10 million per month on payroll. It costs a couple of hundred million dollars a year just to keep the lights on at Facebook.

Compare that with revenues, that while increasing, simply can’t sustain this rapid growth. eMarketer estimates $265M in revenue for Facebook in 2008. The company is still losing money – lots of it. The problem with the growth of Facebook is the monetization model. It is very hard at the current system to monetize any international user activity. And most of Facebook’s growth has come from overseas.

A year ago, according to Comscore, Facebook had 31M US visitors, about 42% of the total. Today, U.S. visitors have grown to just 41M. 19Mn live in Africa and the Middle East. 26M are in Asia. Europe, with 48M Facebook users, has a larger share than the US! Another 16M are in Latin America. Just one in four Facebook users come from the U.S. today.

So there is skyrocketing costs, stagnant revenue numbers, and dwindling cash – What to do?

They will have to find more investment capital through another round but will have serious trouble finding investor’s at the valuation Microsoft’s investment had at $15B. Truth be told, they will probably not be able to find investor’s at their own internal valuation of $3.7B. Which may explain why Yu was fired.

Gideon Yu was in Dubai this week exploring fundraising options. If you know anything about Dubai and their insane development, you can understand why he was there. Despite Facebook publically claiming they are not interested in raising capital at this time, I’m sure the trip wasn’t a personal vacation. U.S. investors just aren’t interested, or aren’t able, to invest at the valuation Facebook expects, even at the $3.7B – not in this economy.

Yu came back to America empty handed and for whatever reason, was let go right after. So the markets in the West, and in Dubai, are not willing to invest in the Facebook, in spite of their remarkable success.

So they can continue their capital quest, sell, or go public.

If for some reason the company manages to convince people that they are a sustainable company with growing prospects for profits, they will probably get their necessary funding, but at a highly reduced valuation.

Or Facebook fails to convince the market, and does not manage to build enough monetization in the site. Value continues its decline, and the company is forced to sell to a larger company. With the heavy user activity and trusty social graph, it would be a very apetizing acquistion target. Think Microsoft as the likely parent. Or maybe Google. Or go even sexier, even Apple.

Or they go public. Zuckerberg is a bit of a control freak, most successful entrepreneurs are, that is fair. My point is that I can’t see him really relinquishing control of the company. The best way to continue operations would be to go public. Yu’s departure and the subsequent job search wording (“looking for public company experience”) is a surefire sign that Facebook is preparing to float on the stock market.

In normal times, this wouldn’t be much of a surprise. After all, companies funded by venture capital usually follow one of two strategies to keep their investors happy: sell for big money to another company, or launch on the stock market and instantly make their FU money.

But after several torrid months, both the Dow and the Nasdaq are currently trading down around 30% from last summer – and, if you’re looking for historical precedents, it took at least three years (and arguably many more) for the markets to recover after the 1929 crash, and as I’ve said before, I think this crisis is worse in many ways due to the complexity of the global economy.

Whatever it would be worth on the open market is definitely not going to be as close to where everyone thought it was, and probably much less than the $3.7B benchmark Facebook believes.

One thing is for sure, Facebook is going to have to react to their financial position quickly, and whatever happens, Facebook as we have always known it is going to have to change.