With upcoming tablets by Lenovo and Asus featuring quad core Kal-El chips, older dual core tablets will surely price dive as the performance differences are quite huge.
I read that the Asus tablet will be released this month, not sure about the Lenovo.
The question is, is the price saving worth buying older stock? I think it all depends on the price differences and your expectations.
Definitely go for the older model. I own a Samsung Galaxy Tab P1000 (one of the first Android tablets, runs Gingerbread), and the performance is fine.
For some reason, the P1000 doesn't seem to be diving in price - I bought it in June for under $300, but it's still being sold for over $400.
That said, Honeycomb tablets have been quick to discount shelves when the newest product comes out. There are likely to be some nice bargains to be had over the next six months.