First record for Canada, apparently - well worth going to see if you're in the New Westminster area and at all interested in birds. It's in a public park (Queens Park) so viewing is no problem. Details here. Here's what a Red-flanked Bluetail looks like (pics of one I took over here a couple of years ago). They breed from northeastern Scandinavia east across northern Russia, and (usually) winter in southeast Asia. So this one's well lost, even more lost than the one I saw.