A question I have been hearing quite a bit on IRC since Firefox 3.5 was released. We don’t quite have the build automation set up to do XULRunner 1.9.1 releases at the same time as Firefox yet, but Nick has been awesome and manually spun some release candidates. These should be pretty much good to go but it would be useful if anyone interested could try them out and report on any serious problems they see. Either just comment here or file a bug and mark it blocking bug 502915.
Without further rambling go get the release candidates.