I have a 2009 Mac Pro that shipped with Lion, and an early 2008 Macbook Pro that I still have running on Snow Leopard. No matter how I try, I cannot get either one to connect to each other. Whether I'm trying to connect via wifi or bluetooth, nothing works. Every time I use Go>Connect to server, neither computer can be found on the other even though file sharing is turned on. About the only thing I haven't tried is hard wiring them together with an ethernet cable. Occasionally I've been able to connect to the Mac Pro from the MBP via SSH, but only VERY occasionally. Maybe two or thee times has this ever worked, all other times it comes up with an error and will not connect. It's a very minor problem, but I do transfer files between the two on a daily basis and it would be much easier to use this method rather than pulling out an external drive every time.