I received several requests to update TargetAlert so that it is compatible with Firefox 2.0. As 2.0 has been out for awhile now, this is a reasonable request, so I finally made a new version (0.8.9.8) available here on bolinfest.com:
All I did was download TargetAlert.xpi from bolinfest.com, unzip it, changed some version tags, and reposted the thing. That means version 0.8.9.8 does not have the features that the 0.9 preview release has, and that the memory leak is still at large.
I do plan to figure out what's causing the memory leak and release a 0.9 version with support for custom alerts. I don't know when I'll have time to do it, though, because I'm caught up in a handful of other side-projects right now and I'd like to get those out the door. (New code is always more exciting than old code, isn't it?)