The Current Version of the firmware is V1.05
If you want to upgrade your firmware, see the BootLoader section of the wiki.
There are a set of modifications made to the firmware by the x0xb0x community, check em out at FirmWarePatches. There is also a wantlist/wishlist at FirmWareRequests.
See FirmWareHacking for a guide on programming and modifying the firmware.