While I was on vacation last week, the newest official XULRunner was spun up and has now been released. XULRunner 220.127.116.11 matches the Firefox 3.0.7 release. For XULRunner developers, most of the changes in 18.104.22.168 are related to security fixes. There are some cookie and XHR fixes in there too. You can also look at the full list of fixed bugs.
Thanks to Dave Townsend and Nick Thomas for getting 22.214.171.124 out the door.
Want to get started building XULRunner applications? We have an article for that.