I've been thinking about proxy patterns a Soprano lately. It seems like a great idea to create a Soprano::Model shim which logs mutable operations to an SQLite database. This would allow intermittent syncs between devices, so a maemo device could have a full local mirror of RDF and communicate with your laptops, servers and desktop machines to keep semantic knowledge in sync.
There are a bunch of nice little edge cases which make this deceptively complex. bnode handling for one changes the rules because identity must be preserved.
I'm not sure if/when I'll hack on such functionality, but I thought I'd blog about it in case somebody else is also kicking around the same ball :)