This is nice:
Yours forever. We don't lock you in. Things uses an open XML file format to store your data. This gives third parties a transparent way to communicate with Things.It's scheduled for release in "summer 2008" (previously "spring 2008").
This review suggests Things might be a rival to OmniFocus, though I doubt they're any better at data import. They claim to have an iPhone client.
Update: It's hard to tell what's going on with them, but I think they put their desktop app on hold to create an iPhone app. The two don't appear to have any current connection or synchronization, and their blog mentions rewriting the desktop app. That's ominous.