Not quite through a client, but I was checking into ping.fm recently for cross-posting via online service... you can set it up to update LJ, but they are missing the rest. I wonder if you can add IJ/DW as a custom URL.

"Settings / Custom URL
Put in your custom URL. This URL needs to point to a script that can accept Ping.fm messages."

That's where I'm stuck at the moment... If this custom url exists for dreamwidth, then it'll make me one happy ping.fm nerd tonight.