Good news for Mac OS X-based Jailbreakers! After having to resort to using powered USB hubs or patching in older versions of files to work around a bug in 10.5.6 that prevented DFU mode from being recognized, the iPhone Dev-Team dropped a note a Twitter to give 10.5.7 the all-clear:
The new 10.5.7 Leopard update is safe. In fact it's more jailbreak-friendly than 10.5.6, since the DFU-mode bug is gone.
So no nasty cat-and-mouse-game shenanigans this time around, and even a slight improvement over the previous -- unintentional -- round.
Only one thing left -- figure out what to do with all those now-redundant USB hubs...