If I did my math right, that's a flat out 20% increase in price, which is beyond an inflation adjustment as far as I can tell.
Anyway, it makes me more likely to "wait till the price drops" or wait till I can get it on discount. If Activision only counts on-release sales as important (which I always thought was a stupid practice, mind, as well-informed gamers often--though not always, of course--wait to buy games until after reviews, bug reports, and patches come out), then they may have hobbled themselves a bit.
Though I can see why they'd figure the increase would be more lucrative--this thread alone shows there are people who won't even blink at dropping 20% more than they usually pay--I agree with the reporter that this is not necessarily a good trend for PC games as a whole. PC game sales often struggle versus console game sales, and one of the selling points PC games had (amongst others, of course) was that they are generally cheaper than console games. If the price equalizes, that's not going to be a win for PC games or PC gamers. Well, I suppose one could take it to mean it legitimizes PC games even more or that they are now equally competitive..... but I doubt it.
Sure, Diablo III specifically will sell and probably sell well if it was even more expensive, but as a trend for PC games in general--in the middle of a recession no less, when people go for the cheaper source of entertainment--I can't see it as a very good idea.
And BTW, I can't see this as a GameStop ploy, because a higher price will just move more people to buy it from Amazon where they can get a bit of a discount.