Thunderbird 1.0.2 was released upstream recently and 1.0 was released a long time ago, but Fedora still sees only version 0.9
Someone created this bug (below) asking for the 1.0 update, and it was closed because 1.0.1 was imminent... Somebody reopened it with 1.0.2 news and I added a caveat/question asking about dependencies...
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=143060
Thanks