Now in CVS near you:
http://common-lisp.net/cgi-bin/viewcvs.cgi/?root=cells
Look for the triple-cells module, then read-me.lisp.
Basically this is persistent data empowered by a ground-up 3cells implementation that is so far a "Cells Light", but pretty decent in terms of functionality. One novelty is that observers are now specified cell by cell.
A long way from being polished, but the core's the thing.
kt