You can download SVN trunk tarballs via the webSVN frontend:
svn checkout svn+ssh://firstname.lastname@example.org/svn/powersave/trunk
When prompted for the password, enter "anonymous". You currently have to enter this twice, once for ssh and once for subversion.
The module you wish to check out must be specified as modulename (either 'powersave', 'kpowersave' or 'wmpowersave'). When prompted for the password, simply enter "anonymous".
We'll try to let trunk stay in good shape all the time but well, you never know. Tell us if you find bugs or have problems compiling.
In the powersave directory do:
./configure --helpgives further instructions (recommended))
This list is probably not complete, but gives an overview: