I'm specifically excited about productivity applications and even third party mail clients (Sparrow, etc) taking advantage of GMail emails being associated with a task.
I agree that this would be great, but I don't see anything in the docs which suggests this task-to-email linkage is available via the API. If I'm overlooking something, please let me know, as I would definitely like to use that.
Sounds like quite doable little project for Google Apps users by combining the Gadgets[1], Inbox Feed[2] and Tasks APIs
Now I would really like a proper Contacts API. For custom fields, Gmail uses one format and Google Apps another. That's a big oversight, and one no one has seemed to recognize yet.
How did the android apps that are in the market get my task lists without the api?
usually some sort of hacked together html scraping