It's all simple economics.
It's going to come down to if sales meet expectations and if customers see the alternatives as viable competition. Monday is a big day. If the rumors are true and Google comes out with a $199 16 gig, $249 32 gig and $299 32 gig cellular model AND customers show and interest, it could put downward pressure on Apple's price.
A lot of folks like to tout Apple as a niche premium brand company. That's true with Macbooks, iMacs and at its new price point, the iPod Touch. But if they are looking for mass sales in a potentially competitive environment, it's going to be much more sensitive to price than those products.
There is a reason the iPhone's subsidized price is $199/$299. As popular as it is, a lot of people would think bit harder about buying one if it was $249/$349.
They've already given themselves a little wiggle room with the stories about low production yeild. The fact the price has already been defended by Cook means that it's on their radar. If demand is soft, I could see a story coming out about production catching up and Apple lowering the price by $30. Apple being Apple, I'd put the odds at about 20% of that happening though.