I've just started using Toodledo and I really like it so far (bought the iPhone app and a Pro subscription). Time to start throwing stuff into the forums ;-).
I did a search and saw brief mentions of using location in the iPhone app and wanted to put my 2 cents in. I have no idea what plans might already be happening, but I've been thinking about how I'd like to see it work, so here goes:
1. Associate multiple locations with contexts.
2. Add a "Here" entry to the main screen that shows what tasks I can do where I am. (I'm thinking under "Starred".)
This way I could do things like linking all grocery stores I use to a single context, then when I am in any of them, tap "Here" and get any items for that context. Tying contexts and physical locations make sense to me, anyway, and it keeps things simple but powerful.