Last month, we saw the Dell Streak's PDMI connector get outfitted with a mini USB adapter for connecting to a computer and various chargers. As it turns out and perhaps unsurprisingly, the device supports USB host/OTG.
We actually should have suspected this back then and could have easily confirmed it with an inexpensive mini USB to USB adapter, but since there's no use living in the past, let's just be happy with the news that powered USB host is secretly supported by the Streak.
Bluetooth keyboards have always worked, and now USB keyboards do too. The easiest way to connect the latter to the Streak is through the home dock, which has a mini USB port on the back (you need this for the USB adapter, of course). Plug the keyboard into the adapter and you're pretty much done. The Streak supplies the power to the keyboard and presumably to any other supported USB device. A USB drive hasn't been successfully mounted yet, though I'm not sure how much effort has actually been put toward getting it to work since there seems to be more interest in finding compatible USB gamepads.
Good news either way and yet another reason to get the home dock.[xda-developers]