download, screenshot. it requires XML-RPC Framework. i've only tested on GNUstep/Solaris, but it should work elsewhere. it probably doesn't work on MacOS X, although it shouldn't be too hard to port.
only the basic posting functions are implemented so far (no editfriends/editevent/etc), and custom friends groups aren't supported.
in case anyone actually ends up using it, i've created a community over at angst_client. (well, it's good to be optimistic :-)