I created a fork with some extra msbuild tasks and targets to support getting, building and publishing packages. We use teambuild for CI.
I import the targets by adding a line to the "common" targets file, so it is automatically available to all builds, then any build that has a packages.config file gets run.
Any dependent packages go into source control, and are then published to our internal feed, so we know the dependencies are always there and can't be pulled. Works well so far, though I foresee a point where there are multiple builds depending
on different versions of the same package that may cause problems.
I also started writing an agent that scans the dependencies feed and looks in the main repositories for newer versions, and notifies people that there are newer versions, but I haven't finished it yet.