The DevTeam iPhone released 2 software tools for the Firmware 3.0 over the week-end:
REDSN0W is a tool to jailbreak an iPhone Edge or 3G even loaded with the Firmware 3.0. It does not work with the iPhone 3G S yet.
PwnageTool is the tool that let's you do similar things by modifying the 3.0 update file prior its installation.
For SIM unlocking, it only works with the iPhone Edge (2G), but not with the 3G or 3G S models.
For additional information: http://blog.iphone-dev.org/
