Edit: I am told that this is a new theme. Sorry, but yuck. Pinstripe almost looks and matches OS X, but on Windows, I have to say no.
Especially in Linux, I don’t like it. Mind you, it’s partially my GTK theme (I generally don’t use GTK at all) but it just doesn’t match or “flow” with the system.
In other news, the project says Firefox 0.9 is nearing completion and may hit RC by Tuesday!