Is the STi strong enough to haul a 1 motorcycle trailer w/ a motorcycle in it?
Is there a trailer hitch for the STi?

Yes it's strong enough, any hitch which fits a WRX should fit an STI (Yesm that's STI not STi).

Which year STI? On anything up to 2007, I concur with Ray. The '08s are allegedly "all new" and I haven't heard of anyone trying hitches on any of them yet.

Yes it's strong enough, any hitch which fits a WRX should fit an STI (Yesm that's STI not STi).
I just figured that looked like STi and not STI.
http://www.flickr.com/photos/adexxx88/1693991695/

Which year STI? On anything up to 2007, I concur with Ray. The '08s are allegedly "all new" and I haven't heard of anyone trying hitches on any of them yet.
A 2004+.

the old badging on japanese model STI's actually was STi. the new u.s. models were changed to STI to avoid confusion or some other such nonsense.