It’s been a while, but last week I started working on the asynchronous location bar patch again. The add-on from past posts will not be updated as there are binary changes that need to be made. I do, however, have some test builds that you can try out. These are built of off mozilla-central, so it’s like using a 3.6 nightly. That means it may not be stable, and you shouldn’t use this with your default profile (but feel free to copy your places.sqlite file into a new one to really hammer on it). If you are interested in trying it out, the builds can be found here.
Your feedback is appreciated!