i'm quite interested in this as well. although the last update to the titanium pb's has been almost three months ago, i can't seem to find any articles or benchmarks about them.
i recieved my ghz tibook about ten days ago, it's equipped with the 64MB version of the mobility radeon 9000. i've tested most of my games on it. while all performed just fine on it, quake 3 was the only one where i enabled the frame counter and as i wasn't able to look at it all the time my numbers aren't to be taken too serious. at 10x7, max settings, "s_chunksize 4096" enabled in the config, i got around 120 fps with just walking around, about 100 fps with medium action. with major action going on fps were around the 80s.
the other games include: warcraft 3, diablo2, medal of honor allied assault, RtCW, the jedi knight II demo and Black & White.
i have yet to see choppy gameplay with this baby. ^^