Cabel, thoughtful dude that he is, posted a status update for Panic's applications and Leopard compatibility that runs down what works and what doesn't come Friday night. Most of the Panic apps will continue to work in Leopard, some with minor issues (Transmit) and some just fine (Coda); the one major exception is system icon tweak tool CandyBar 2, which unsurprisingly is not yet compatible with the new Leopard "big icon" format. The good news for CandyBar fans is that version 3, with full Leopard goodness, will be available by the end of November.
As other Mac developers announce Leopard compatibility info (like RealMac did earlier for Rapidweaver), we'll be sure to let you know. (Pssst. Developers -- over here! Be sure to let us know when you update your apps for Leopard, and we'll pass it along.)