I've been noticing that the new Adobe Flash is working better within Safari on my 12" AlPB.
I occasionally keep Activity Monitor open in a corner where I can see the CPU usage graph. In 10.4.6 the graph indicated lower usage after installing the new Flash, and the effect persists in 10.4.7. To me, it seems that Safari is consistently gobbling up less of the %CPU, which means lower heat, less fans.
Try it out for yourself, and report back if it seems to make a difference. You'll have to monitor the graph for awhile before upgrading so that you can get a sense of what's normal under your everyday pattern, and then check again after upgrading.
Edit: thought I was putting this in the applications forum==oh well, mods can always move it...