Here's an interesting quickie.
Mapbox gave put together a fascinating map of the point of origin of over 280 million geo-tagged tweets. Also, the map lists the device from which they were sent.
Here's Canberra - loooots of red (iPhone users) on here, but interesting pockets of green (Android) too. I think the pink blobs must be a single, solitary Blackberry user getting around town - poor RIM.
(via Daring Fireball)