At the moment we don't support publishing from within MSBuild, though it is possible to add MSBuild targets to .pyproj files that will be run by MSBuild.
If you use "@(Compile)" or "@(Content)" as an item list within the .pyproj then you won't have to reproduce the file list, and if you have other settings stored in the .pyproj then you can access those as well.
We may create some .targets files for our next release to support this use (I'll create an issue to track this), maybe including unit tests and syntax checking as well (you can probably use an Exec task with python.exe for now to at least test that
your code imports).
I'm not sure how well versed you are in MSBuild, but the main reference is at
http://msdn.microsoft.com/en-us/library/vstudio/dd393574.aspx and we'll be happy to help out if you need it (especially if you're willing to contribute a script back...?).