It makes a pretty good job of displaying all your Backpack data just the way Backpack does, so your information looks the same when you’re offline as it does when you’re online.
I have a feeling that we’re going to see many more applications like this in coming months, as webapps get more popular and gain more users. Most of the smartest webapps (like Gmail, and everything 37signals is working on) are fantastic tools but being offline kind of puts a spanner in the works.
What these webapps need are simple-functionality desktop equivalents that allow you to at least view your data, better still edit it too, and then automagically sync themselves with the online version the next time you’re connected. I’d be astounded if Google wasn’t working on something like this for Gmail users.
In the meantime, Backpack users can get ahead of the curve by trying out PackRat. A licence costs $25, not much more than one month’s Backpacking. If you’re increasingly getting frustrated with offline time, it might just be the solution you’ve been looking for.