Scotia, I think you've identified my biggest challenge, which is demonstrating an understanding of the British system. I'm slowly getting my head around it, but it's so different from what I'm used to that there's a pretty steep learning curve. I recently applied for a lecturer position that I was quite well qualified for, but didn't even make a long list. I think my inexperience with UK universities is going to slow me down.
Wegie, I've had my eye on Open University. I get the impression that it is far more respectible than an online school (Phoenix, etc) would be in the States.
I will watch for terms like sessional and fractional posts. I would not have had any idea what those meant, so this has been really helpful. Thanks, everyone!
The Open University is definitely looked upon very differently to Phoenix University. I know very highly respected academics who work or have worked at the OU, and have had a couple of respected colleagues with OU degrees. In my experience they provide very good support to their tutors, including good training (I did some tutoring for them while a post-doc at another - highly regarded - UK university who were happy for me to get teaching experience from the OU).
There are lots of reasons why you may not have been short-listed for a position that have nothing to do with you being from the US. I would not be too concerned about one failure to get an interview. If you are in a high supply field, that may be a barrier, rather than being from the US specifically.
I remember a thread some time ago - don't ask me when: I seem to be a longer-standing forumite than I remember - about the differences in language between the UK and US when talking about degrees, courses, marks..... That might be useful if you can find an adequate sacrifice to the fora search engine gods to help you find it.