I'd be curious about this topic, not because I'm pro or against this approach. I've worked on both sides of the spectrum (web app wrappers, full native and lately a hybrid, which is more complex than Basecamp) and it seems like a fine balance needs to be reached. You're "fortunate" that you keep the UI pretty slick and simple. And I say "fortunate", because I know this is actually a choice.
These will be very helpful to the mobile community. It's great to read about larger scale services and how they tackled mobile. It was great when LinkedIn shared about their new mobile app and the development efforts.