I wouldn't call the difference between the iPad 2 screen at 1024x768 and the Tab 10.1 at 1280x800 a huge difference where Apple or anyone else felt like they needed to play catch up. If you deliver the first viable tablet to the market it makes it pretty easy for competitors to incrementally one up the specs.
The new iPad trumps the Transformer Pad Infinity. The Inifity has a 1920x1200 resolution which is a step up from anything else on the market. However, Asus was not able to bring it to market soon enough before the new iPad announcement. It also looks like the iPad will hit stores before the Infinity as well.
Now 2048x1536 resolution IS A GAME CHANGER. No one is even close and they won't be for awhile.
The latest rumour is that Samsung is set to announce a device that has a higher resolution with an AMOLED display. I'd be interested to see what they have in store. In the mean time, I'm interested to see the new iPad up close when they have demo models available in stores.