"8Ball Allstars" for the Nintendo DS is due to be released on 18th April, 2008.
ChoicesUK have it for Pre-Order for £14.99 (inc del.)
You can get cashback through the usual sites (e.g. 5% Quidco, making it £14.24)
The next best price seems to be £17.98 from Amazon.
This is a pool game, that takes full advantage of the Nintendo DS's features. I'll add some links below.