Just got my Raspberry Pi today :)
Can't wait to use it!
The Pi is indeed I2C capable. Only known limitation is that it is only capable of being a master, not slave and it has been reported that the Pi has problems when devices on the bus are keeping the clock signal low outside the Ack-part of the transmission.
I don't know whether the first issue is hardware or software related.
The latter is a common I2C trick, but is not part of the I2C protocal, so not an error perse.
(I have a cunning plan for a robot, featuring my Pi and 2 ATMega328p, using and I2C and programming the ATMega328p over SPI using the GPIO.)
I am very interested to hear about your experiences with Raspberry Pi.
I read something that implied it could do i2c. If so, that might make it easy to interface to PIXAXE chips.
I am currently planning on using 2 to 4 PICAXE micros in my second robot, but would love to upgrade the master to a Pi, if it could handle that.
Good luck and let us know how it goes,