I slammed them for the upgrade and calling it new yesterday, so I'm going to eat humble pie a bit now and say good on 'em for actually officially commenting on this and throwing a few crumbs out there. I have to think they've had a big (negative) response via email (and reading forums like theses, and various websites out there probably), and they've responded about as much as I think we could expect them to.
I'm guessing that really the vast majority of people that would have been buying yesterday's minimal tweak of the 2010 Mac Pros would be people who really need to buy Mac Pros anyway, and now will be getting more stock RAM and better CPUs as standard, instead of having to add those things themselves. For people like that, who absolutely need a Mac Pro (maybe to replace a heavily used older model in a production environment of some kind, for instance), this won't make any difference.
Apple are giving a clear 6 months+ notice that this is it for now, so if you absolutely need one, buy it. It you don't, and you can wait to see what they do next year, great.
Also perhaps worth mentioning is the period AppleCare lasts - 3 years. (Edit: as snberk103 did in fact do right before me by mere seconds!) It would perhaps be unsurprising to see an all-new Mac Pro in the period where a lot (possibly a majority even?) of AppleCare agreements are coming up to the end of their service period. I imagine Apple sell more Mac Pros when they're quite new, and I'd speculate the people waiting to upgrade the day they go on sale are also more likely to be the AppleCare purchasers.