It seems Android 2.2 is just not good enough for Acer. They've promised 2 Android tablets, delivered by the end of Q4 this year, but they're not going to hold that promise, because instead of being just one of the dozen or so manufacturers to release an Android 2.1/2.2 tablet this fall, they'd rather be one of the very first to release an Android 3.0 tablet.
If they do it right, and make tablets for a very competitive price, but with the best specs on the market, as we're used to from their laptops, they have a chance to gain a portion of mindshare from early adopters.
I don't think whatever comes out this fall is going to be terribly impressive, except perhaps, the Notion Ink Adam tablet, and Motorola's Droidpad, which Verizon is going to push hard, mostly because Android 2.1, or even 2.2 is not ready for the tablet form factor, so Acer is not going to miss on much. Android 3.0 is most likely going to be made with the tablet in mind, so Acer won't have to risk disappointing their customers with a worse tablet experience. They can release a tablet that rocks from a hardware point of view, but also from a software point of view, as well.