Shift (as well as Kante and Knoten) have been available as source for a while now, but installing from source is not really a lot of fun if you just want to try it out.
So, now I finally got around to putting together an installer package for Shift, that will just install the binaries on your computer! It contains the Shift application itself, as well as three plugins (AddressBook, iCal and BibDesk). So, no more excuses - just download the installer, install Shift, and start creating RDFa!
When I get the time, I will put together a proper readme file. In the meantime, I hope you will find Shift self-explanatory.
Oh, and please send plenty of bug reports.