AIM Productions has released a great looking pool game: Pool Challenge! Per game's web site, here are some of the features:

Smashing high-res graphics
Original control method: use your stylus as a real pool cue!
True physics, with realistic ball rotations and spin
Play 8-Ball and 9-Ball against the computer or a human opponent
Options menu: adjust sound, music, sensitivity and CPU difficulty
1-player practice mode
Resume previous games
Realistic sound effects and background music
User-friendly interface
In-game help screens
Compatible with most Pocket PCs (XSCALE,ARM) running Pocket PC 2000, Pocket PC 2002 or 2003

We are working on an in-depth review. At the mean time, feast your eyes on these: