I have long been disappointed in the "baby-with-the-bathwater" approach taken by Compiz and friends.

I just saw Thomas's announcement of Iain's and his awesome work in Metacity 2.21.5. I just downloaded it and after the trivial ./configure, make, make install, the magic happens! The below screenshot is from my crappy Intel GMA on a laptop. That is Gnome Terminal recognizing the available ARGB visual and using it for accelerated alpha blending.