We don’t have a lot of details yet, but San Antonio-based Rackspace stands to raise around $400M with their Initial Public Offering (IPO). They’re taking the same route as Google, in terms of using an auction-style offering to help maximize the funds raised.

The financials are pretty interesting. The company has grown revenues very rapidly in the past few years, but it has also grown overhead pretty quickly. While revenues from 2005 through 2007 have grown from $138M to $223M to $362M, net income has not grown as sharply and actually went down from 2006 to 2007. You might be able to get away with that while you’re private, but Wall Street will hammer you for numbers like that.

The company says it has invested heavily in sales and marketing, additional data center capability, and their new cloud computing architecture (MOSSO). A quick search of comments about MOSSO reveals mixed reviews on the cloud technology, but high marks for support (which the company is know for).

It appears that key executives invested in the company through their personal investment companies, right alongside the venture investors. Management has some pretty good skin in the game, which also means they stand to make a killing when the lockup period expires.

We couldn’t find company founder Richard Yoo in the filing, which must mean he owns less than 5% of the stock. Not too surprising given the $40M in capital that has been poured into the company.