Well I've been printing using the standard (well slightly modified) pronterface on my raspberry pi straight to my mendelmax. I have not been able to get the wifi working, but I do have a shared drive that I can access with my Mac Pro. So my tool chain is to download the stl, slice it then save it directly to my raspberry pi. I then use vnc to run pronterface and load the file and start/monitor the print.
The one big issue I've run into is the memory on the Pi. I still have the 256mb version and it will do fine for probably 75% of the things I've printed. But on complex objects, most notably the x carriage for a mendelmax, it runs out of ram and shuts down pronterface. I can still print from the sd card, but a newer version of the Pi with the 512mb will be ordered shortly :)
Other than that the latest distro is much faster, I'm seeing much better performance when I vnc in, and I can actually move windows around and use it while on a 4g connection.
I'll probably be ordering my new pi this week, and then anxiously awaiting its arrival :). The current one will probably be going into my CJ as the main controller for all the devices I want to add in it.