At long last, I've found a solution to streaming last.fm radio through MPD.

http://bash.viharpander.dk/#mc has a collection of utility scripts for <tt>mpc</tt>, one of which is the <tt>mpf</tt> script for last.fm.

to install, extract the zip into a pathed directory (it contains three scripts, which bomb the current directory). Run mcf once by hand and it will run through a simple configuration wizard to set your last.fm credentials.

Then you can run mcf to enqueue streams in mpd:

mcf 0.3 gives you easy MPD access to last.fm radio stations. Run 'mcf –setup' to generate a configuration file before use.

Syntax:

 mcf <search key> <search term(s)>

Search keys can be

 a for artist (e.g. 'new york dolls')
 f for last.fm's global tags, only one accepted (e.g. 'funky')
 l to pick a tag from a list of poular tags (does not require
 search terms)
 r for a group's radio station (e.g 'mpd')
 u for user's radio station (e.g. 'musiclover8462')
 n for user's neighbourhood radio station (e.g. 'musiclover8462')
 s for a specific last.fm address (e.g. 'lastfm://play/tracks/10413')

Last.fm is fairly strict with redirects but you should be able to get away with omitting initial 'the's and not capitalizing any letters. All search terms except user name and lasf.fm address can consist of multiple words. Sadly there does not seem to be a way to combine multiple tags.