2012 is making my head explode. Two things that used to be hard and out of reach for the "poor" are becoming mainstream and easy for anyone to access....college level education and mapping. I'm going to be honest, mapping-for-all is more surprising to me than the recent education explosion. It is traditionally considered a "hard" problem, that requires understanding or mastery of a few different disciplines just to whip it into shape. Absolutely amazing! I haven't been this excited with tech development since the "old" tech bubble. (ask your parents!)
Cool! Any writeups yet on how it compares to existing solutions like Mapnik, TileMill, Tilestache, etc?
Not really, though I'd say it's smaller than Mapnik. TileMill (backed by Mapnik) is an amazing GUI for styling maps, and TileStache is an awesome caching server. But, really at it's heart all SimpleTiles does is convert spatial data into an image, and does that by relying on GDAL and Cairo as much as possible.