It's the watch/trust thing - have a look at "subscribe/access" at http://wiki.dwscoalition.org/notes/Dreamwidth.org:_FAQ#Subscribe.2FAccess and the server implementation details at http://wiki.dwscoalition.org/notes/WTF_Backend (maybe there's more, I'm still finding my way around the wiki)

Oh and I used a Qt-based XML-RPC implementation at http://code.google.com/p/qtxmlrpc/ (although had to fix a few things as it didn't work right away).