It sounds like Socialtext have pulled off masterful feat of technology: taking a web application and making it available offline. Such a goal is really sound: so many of us live in a ever-more mobile world, the frequently disconnected worker is usually excluded from some of the best apps.
Take, for instance, the case of IBM, where 40% of the total population is mobile!
TWiki has got code that can facilitate it to do a similar thing, in TWiki’s case you’d run an instance of TWiki on your laptop and synchronize with TWiki’s SyncContrib. SocialText unplugged is based on TiddyWiki.
The difference that SyncContrib is not production code – I cracked what I thought was the hardest (most interesting) problem, the peer-to-peer synchronization, and have hitherto offered to finish it if someone is willing to pay for my time. I did have one offer but I could not be sure I could complete in the budget they were offering, so I turned it down.
This can be a problem with Open Source projects. Maybe someone will contact me about SyncContrib: I do have some time available in the next couple of weeks to crack on at it if someone can throw me a contract.