Connecting a BlinkM to a PICAXE
Do you mean standard i2c speeds or something specific to picaxes or blinkM?

"The standard clock (SCL) speed for I2C up to 100KHz. Philips do define faster speeds: Fast mode, which is up to 400KHz and High Speed mode which is up to 3.4MHz."

quoted from http://www.robot-electronics.co.uk/htm/using_the_i2c_bus.htm

EDIT: Found this: http://getsatisfaction.com/thingm/topics/picaxe_communication which should give you at least something to test your setup with.