I mentioned this awhile back on twitter, but UppercuT (UC) has support for Mercurial for versioning your assemblies.
In the settings file, all you need to do it tell UC to use hg.
When you build your assemblies, they will use the changeset number in the version, and in the informational version, you get the hash, just like you do when using Git.
Pretty sweet. By the way, UC also supports .NET 4.0 as of last week. With this knowledge you shall build.