I too would love a Luxeon running on a single AA battery - with BOTH good brightness and good runtime.
Unfortunately to my knowledge at the current state of LED technology one can have one or the other, but probably not both.
A single AA just does not seem to have enough to drive a bright LED at current LED technology -
I think a single CR123A may be better suited to get both respectable brightness and respectable runtime.
Of course I'd be really happy to hear otherwise.....
then there'd probably then be the problem of price -
like people say - you can have 2 out of 3 -
brightness, runtime, price -
with a single AA - probably one can't even make 2 out of 3 - for now.