I taped an interview with TheStreet.com TV. One of the topics covered was the rumored $300M-$500M investment by Microsoft into Facebook.

Do I think Facebook warrants the $10B-$15B RUMORED valuation? Who knows. Once you get over a few billion, I stop counting. But I do know that Facebook is worth MUCH, MUCH more in 5 years than it is today.

Here are just some of the stats:

• Over 200,000 people register for Facebook each day.
• 40 million registered users (of course, this number will be off tomorrow as the train rolls on).
• Half of the users are outside college, compared to ZERO in Sept. 2006.
• More than 40 billion page views each month.
• Average visitor stays 20 minutes.

While the business has been able to attract and retain users, it is just entering its revenue inflection point. Its growth is starting to look like most wide-eyed business plans that cross my desk — the inverted hockey stick that usually never happens!

The real questions is: What does the business look like in 5 years when ad dollars continue to shift online and 300 million people use Facebook worldwide to connect with friends, have fun and hang out? More than a third of all media time is spent online. But online media dollars represent less than 10 percent of the total ad dollar pool. That’s gotta change, right? Add 300 million more users in the next few years, and you’ve got a monster, monster business.

So yes, I do believe Facebook is worth $10 billion. And if I were Mark Zuckerberg, the founder, I’d do the following:

• I’d raise $500M from Microsoft (even if it’s at a measly $10B valuation).
• I’d push the board and investors to take $250M off the table. You’ve created a killer business. You’re hot. It may not last. So why not put some money in your pocket. Assuming he owns 30% of the business, Mark would put $75M in the bank. This is well earned money. The other investors don’t need the money. Mark does. Start living a little so you don’t get burned out.
• I’d take the other $250M and invest, invest, invest. Forget about the IPO. Forget about a sale. Invest in the best product team you can buy. Invest in technology. Invest in a worldclass sales organization. Invest in Buddy Media (just joking). Continue to focus on the business and great things will happen down the road.

A sale right now just doesn’t make sense. You’re making the right moves. And you seem to be having fun doing it. Working for yourself, making your own decisions and growing your own business is a great thing. Appreciate it. Don’t take it for granted.

Good luck Facebook. I’m rooting for you!