Well, It's not necessarily dealing with the ELM327, but this looks like a FANTASTIC solution.
No longer getting developed.
Apple is currently not allowing developers to use Bluetooth for this purpose. The only real connection is via Wifi.
My initial "assumption" was that if you're connected via Wifi, then your 3G data is disabled and therefore you cannot use data while using the OBD-II dongle. This information is wrong. If you put your data connection in proxy mode, your phone will still connect to data through 3G, even when connected to the dongle.
This works very well except for the minor issue whereby the gauges poll once every second as opposed to constantly polling in real time with what's actually happening. This makes for a choppy user experience, but it still works well.