Here's how to get it going. First, download the correct version (Linux PowerPC for your PowerPC Macs) and extract it to any directory in your home folder. Then either use your file manager to open that directory in a terminal, or in a terminal type the command
cdpath to directory holding the btsync binary. Then get the btsync daemon running by entering
Nothing happened. That's 'cause you have to use the web interface, silly! So get your IP address with sudo ifconfig (among other methods), fire up a web browser and go to yourIPaddress:8888/gui. In my case:
Next you should see the web interface where you can click Add Folder. Type the path to it, /home/yourusername/whatever, and then click the generate secret button. You will enter that secret into your other computer to sync to that folder. So do the same thing on your other computer. Extract the binary, startup the daemon, bring up the GUI, and add a folder to sync, this time entering the secret from your other computer into the Secret field instead of generating a new one. Now the syncing should start--Snow Leopard users may see a delay of up to ten minutes which BitTorrent Labs implies is strictly the fault of Snow Leopard ;)
I got pretty much full speed out of my wireless connection, though I haven't tested it over ethernet so I'll defer comment. Also, in their Get Started guide, they mention disabling the "Delete files to Sync trash" option means your deleted files will instead go to your system's trash folder, but on my system they just disappeared. So be mindful of that. Also there's no versioning yet, but I'd expect that in the near future. But overall, pretty cool stuff.