Who ever said that good things don’t come from Slovenia? Jay let me know that Vodafone out there has officially released OS 18.104.22.168 for the 8310 via this thread on CrackBerry Forums. (Nice work Ghostshell for spotting this release)
Right now there is only a direct link at this link.
You will need to delete the vendor.xml file to get this to work on other carriers. You can find the instructions in the forum thread. Or better yet just use the free and extremely useful CrackMem utility.