My current conspiracy theory is that Eric Schmidt, former Apple board member and CEO of Google, told Steve Jobs that the matte screens were more popular with Apple's customer base and so now to prove him wrong he's only offering matte screens in-store on the 15" hi-res and 17" i7. I think when the total number of glossy screened ordered from the on-line store turns out to be higher than the number of matte screens ordered on-line and sold in stores Steve Jobs is going to call Eric up and say "I told you so I told you so!!!" and stick his tongue out at him.
Hmmm, then again maybe I'm off-base with that theory.