Jedi Knight II should work well in most places, Newerwinter Nights should work well too.
Yet, you can't expect it to run the next generation of games really good:
Doom III is an excellent example. The demo at E3 ran on the next-generation ATi graphics hardware and there WERE slowdowns in some places.
UT 2003 won't be that taxing for your PBook, yet, you won't be able to run it using the highest resolution and maximum details.
That's it. Since you asked if the TiBook supported new games for the next couple of years, the answer is no, definitely.
Steve