Does it actually work? Wellll.... sort of.
Observations so far:
- Galaxy Nexus: Works fine with OTG cable, huge power budget.
- N7: Works fine with OTG cable, huge power budget
- Xoom 1: Some things work, some don't. "Simple" USB ops seem fine, but complex stuff (like driving a USB wifi NIC) seem to blow up.
- Motorola Razr Maxx: This one is extra weird. USB host exists, but requires a +5v backfed power, with enough amps on it to charge the phone in host mode. That's a hell of a thing. The Razr also enforces an excessively small power budget (so small I'm not sure it allows ANY device to function) unless a hub is in the chain. It doesn't even have to be an externally-powered hub! (Well, except that you have to externally provide USB power regardless).
- HTC One V: AKA the Ninja Phone, is reported to have non-working USB host due to kernel bugs. Custom ROMs only?
- Other phones: No idea, let me know in the comments?
I'm working on a USB power injection board which provides micro-usb ports for phone and battery packs (on the assumption that everyone has a ton of micro cables handy by this point), an integrated one-port USB2 high-speed hub to handle power budget problems, and a standard female USB socket for client devices.
Could you solder together some cables and get the same effect? Sure. You could also use a no-logic power splitter board like one I made earlier. But it's really ugly, and prone to falling apart at the worst moments.
So I'd rather do it cleanly.