Have you given up on the idea of getting married? If it's true that UK should accept any marriage that is legal in the country in which it was performed, that may still work.
I would not trust any marriage in the US to fit the bill as we have a Federal DOMA and the federal gov will not recognize a same-sex marriage.
However, you could get married in Canada, as it is legal there, and there is no residency requirement to get married there. The summary of UK immigration law did not say that the marriage had to be performed by or recognized in the country of your residence -- just by the country in which it was performed.
Just some thoughts. Good luck! And as someone else mentioned, there will most likely be the UK civil partnership registration eventually, but I heard an estimate of Oct 2005 for that actually going live.
