I’ve played around with it on the iBook. It’s built on the Ruby on Rails framework, so it’ll run on more or less all platforms that will support Ruby; you’ll also need MySQL (although I’m having a go at making it run on Sqlite just for the hell of it).
Like most Rails apps you can start it and run it on the built in Ruby webserver (Webrick) on port 3000 by going into the “scripts” directory and issuing a command like:
[iBook:~/Desktop/tentacle/script] ruby server --environment=production
assuming you’ve got your database config all sorted, of course. This saves trying to get Apache sorted out to run it instead.
I like it. I’m not looking for new software for this site right at the moment, but Tentacle bears watching for when I do.