I've only seen a rumor posted on this forum that the beta 10.5.5 (developer release) contained a fix for it. However I cannot find anything concrete.
unless you roll back your drivers, i don't see how you did that. I tried doing that and my mac just started to hiccup. Wasn't worth the aggravationDiablo II works perfectly for me 10.5.4
unless you roll back your drivers, i don't see how you did that.
ATi graphics based Macs do not have the driver issue.
Friend of mine has 10.5.5 and it fixed Starcraft, unsure about Diablo II(most likely fixed as well).