The big feature I'm waiting on in Firefox is live reloading/editing for scripts.

It's a huge advantage to be able to pause a script in Chrome, edit the source code, and have those changes injected back into the script. Chrome will even rewind the stack if I edit a line behind where the script currently is.

I use Firefox for all of my personal browsing and for some of my development. But I really miss that feature.

Edit: that and making it easier to debug Node from Firefox. It's still kind of a pain in that area.