The content and timelines of version control systems should be ripe pickings for a graphic metaphor, but I haven’t seen any good examples of it yet. Versions treats them primarily as hierarchical lists to be clicked through. I’ll have to test before deciding whether this works in practice, but it makes sense in the telling.

Requires XCode Tools for filemerge and diff display, so this might not be the thing for casual web developers. The beta is free, while version 1 is marked as payware with no price set yet.