what is ogg?

i've had soo many people tell me that ogg is better than mp3, how? i know ogg is opensource, but as long as the bit rate's the same does it really matter in terms of quality? or does the differnce matter in size ?

There is a Vorbis codec available from I forget where for iTunes. There's also a WMA codec from flip4mac, but I haven't tested it to see if it allows iTunes to support it.

I expect that the reason they don't support decoding is that the engineering costs for it and on the iPod would be more than the number of people who would use it. And they certainly wouldn't support the encoder, since they're marketing AAC.