Tilestream-on-dotcloud is a project mainly written in Python, it's free.
To deploy tilestream on DotCloud::
git clone git://github.com/jpetazzo/tilestream-on-dotcloud dotcloud push tilestream tilestream-on-dotcloud
Then go to the URL shown at the end of the push.
By default, it will download Haiti Terrain Grey tileset.
If you want to automatically load other tilesets, edit
dotcloud.yml and change the mbtiles list under
the environment section.
More about MBTiles: http://mapbox.com/mbtiles-spec/
More about TileStream: https://github.com/mapbox/tilestream