Thunderbird 3 schedule was announced and Fedora included a pre-release
version based on the announced schedule and Thunderbird 3 was delivered
late but since Fedora had already tested the pre-release, it went along
with it and pushed the general release of Thunderbird 3 as an update.
Similar things have happened in Ubuntu as well, for example the last LTS
release included a pre-release version of Firefox and current release
includes a development snapshot of GRUB2. Anyone who thinks Fedora is more
experimental than before hasn't been paying attention to some of the