There are two new security updates coming up this weekend. They are BIND package which affects only Slackware 13.37 and -Current, while Thunderbird packages are being updated back to Slackware 13.0.
While Mozilla has released Thunderbird 5, it seems it will take a while before that version comes up in Slackware-Current. I think Pat is still evaluating Thunderbird 5 before he decided to include it in -Current. It's a nice update though, because it's now based on Firefox 5 codes, which has previously included in Slackware also.