Apple released the first update for Leopard, version 10.5.1. Which includes many fixes for the new OS. You can find the full list at Apple’s site.
Apple also released what might be the final Mac OS Tiger update (10.4.11). You can visit the feature page at Apple’s site. It includes the final edition of Safari 3.0 and many updates.
For some reason it did not appear on my software update so I have to download it manually.