Rackspace's first day of trading ended with shares at $10. IPO price was set at $12.50, so that's a loss of around 20% in value (and I'm pretty sure a lot lower than what the shares were valued at internally when it was still private). While I don't think it was ever reasonable to expect the value to skyrocket to $200/share (I mean, it is just webhosting after all), I think $10 is a little unfair by the market. Interland suffered the same fate during the start of the dotcom implosion... and there's no way in hell I'd ever equate the value of the two companies.
On a personal note, assuming that I'd stuck around with company, could exercise my options at the strike price I had for today's closing.... I would have made more money if I'd gotten an $5K bonus each year than from the IPO. Moral of the story: cash over stock, kidlets.
But any rate, congrats to the folks still there... enjoy the payoff :)