You know, the other day I was using the PandoraFM mashup site and it wasn't submitting to my last.fm account. I thought it was just a fluke, but perhaps the two are related and something about the last.fm site has changed.
edit: it looks like there have been some changes to the API in the last month or so http://history.swik.net/Last.fm/Plugin+API I don't know how to, like, change anything though.