Well you got me there - I have been thinking about.
You know what would be
great if someone could explain how to use (or even code a GUI) for x264farm which basically will split a single encode over the network (just like xgrid) to your other macs. Truly distributed computing
More info
here and
here
don't hold your breath
the only good video authoring tool GUI that supports Mac and is written from the ground open instead of just passing files to an open source application is Handbrake. I'd suggest learning how to use the command line if you enjoy a challenge, or how to change the H.264 options in Handbrake to speed it up. There's a good page in their wiki about it, and the easiest ones to lower for more speed are the output resolution, "subme", and the motion estimation method.
Using the command line has an extremely steep learning curve, as you need to learn terminal, how to compile open source programs, how to get them to compile correctly on mac, which programs work best for your workflow, how to write a shell script to integrate the programs, how to make Quicktime happy, which options to use, how to use those options, how different options affect speed and quality, AND what apple tv supports.
By far, the best option right now is to just trust Handbrake and its presets. If you plan on altering a preset, post in their general forum exactly what preset you're starting from and what exactly you're changing, and what you need it to support. They're one of the most angry forums I've been on, but well-deservedly so, they have to deal with a lot of crap from people who change presets and then wonder why they won't work with their devices, or people simply complaining the app is crashing with no information about what they were doing at the time or what the error was.
Also, they have to do a LOT of work, writing video conversion software is very very very hard. Most programs like VisualHub, or "iPod conversion" software you see is just a GUI written on top of ffmpeg, the most popular open source video tool.
