but being one of the empeg cult how does empeg get on with OS X as mac calls it
Just fine if you use Jemplode.
want to do all the usual stuff like streaming file taxi etc
Streaming and file taxi are specifically done with the Hijack kernel, using standard HTTP and FTP protocols. Those are computer-independent and should work just fine on your Mac.
Also is it possible to update firmware using ibooks
Not at the moment. You currently need a Windows PC with a serial port to run the full upgrade utility.
I seem to remember someone had written a way to upgrade the player using hijack and some FTP trickery, but I could be thinking of something else.