Unfortunately, if you use cash a lot, you'll have to manually input these transactions. Davel says that they are working on this problem and will launch a solution soon when the mobile site goes live.
The service, accessed via www.22seven.com, is available to all South African online banking customers. Customers receive free access to the service for 30 days, after which it is R70 per month.
I suspect a few people to scoff at the idea of paying R70 for this service. I'm trying it out for free first and I have a sneaky suspicion R70 is going to seem like peanuts when I (hopefully) start realising how much more money I have.