kg4wsv, thanks for sharing. That's a smart way!
WilliamK, I've been looking for a while and couldn't find a thing. The I2C library in arduino is like an onion, layer after layer. There's like wire, TWI, etc. I couldn't find anywhere to access status bit on the bus. I think I made a post and didn't get much response. My guts feeling is that it is not possible unless you want to modify the library. Currently the I2C library just takes a whole bunch of bytes, and only writes the bytes when the communication is terminated by the call Wire.endTransmission().