Myowndelicious is a project mainly written in Python, it's free.
A delicious bookmarks to can call your own
This is an unambitious attempt at preserving user bookmarks from delicious servers before Yahoo shuts down the system (we now know those rumours were greatly exaggerated). It should run on top of Google's App Engine (I know - it may also be shut down in the future) and should be able to import Delicious bookmarks (even grab them itself, if the user gives this app their password - and that's one reason why this application is open-source: the user must be able to deploy it on his own GAE instance).
It's licensed under the Affero flavor of GPL to ensure no lock-in from any entity that decides to use it to build a social bookmarking system.