K, got the bmp085 working. There's an error in the Maple Native documentation: SDA and SCL are reversed for I2C channel 2 (haven't checked the other channel). Of course that doesn't matter for bitbanging, but it did serve to confuse me on which pin was doing what.
I'm still having problems with an atMega as a slave. I have I2C working with an Arduino Uno as Master and an atMega as slave, but the same atMega won't respond to I2C commands from the Maple Native.
Since this is no longer about the bmp085, I won't continue to fill up this thread. Go here for the continuation:
http://forums.leaflabs.com/topic.php?id=1307#post-7934