Many thanks folks. I wound up opting for a hidden form (thanks for the twit Laurian!) - it allowed me to do a sweet RESTful POST and because I didn't need anything back from the server there was no need to get my hands dirty with iFrames. Maybe jQuery could benefit from such a feature?
Anyhow I did a little write-up of the options I found for cross-domain Ajax at: http://blogs.talis.com/n2/archives/770 Cheers, Danny.
