Sunday was Last.fm's first Hack Day (and my first Hack Day too) a great opportunity to get together with a bunch of other developers, enjoy a steady supply of free food, coffee and beer and spend the day hacking away at whatever Last.fm-related projects we could dream up. I particularly liked Neil Crosby's Last Genius which builds a playlist of similar music based on a single starting track and Matt Ogle's Songcolours which draws pretty graphs based the most common words in the lyrics of your favourite songs.
I spent the day playing around with SIMBL, Spotify and, of course, the Last.fm API trying to build a Spotify Scrobbler. Progress was slower than I would have liked and I spent most of the day trying to figure out Spotify's internal APIs and following various dead-ends (reverse engineering compiled software is tricky), but it was good to learn how to write SIMBL bundles and by the end of the day I'd managed to hack together a working plugin that was aware of when a new track started and what the track and artist names were. It seemed a shame to leave it half done, so I spent some time when I got home adding scrobbling capabilities, and you can now find a working Spotify Scrobbler over on GitHub (if you want to use it you'll find instructions in the read-me file). It's not particularly polished, but I'm pretty pleased with how it turned out. All in all, a good first Hack Day.
As of 18th December 2008 Spotify has built-in scrobbling support.