Yes, it won't sting you. I saw plenty of these in Fairlands Valley Park, Stevenage, late last summer (2009) but was unable to get a photo. These are outside Stevenage, in the lovely countryside of Hertfordshire. In fact, because I'd seen them in late summer, I didn't really expect to see them again until about the same time of year, but apparently they flower between March and November! Only one of the flowers on this one had opened yet, though (although two days later all of them were open).

When I was a child, a friend said nettles won't sting you if they have white flowers. I never tried it though I've always remembered it. To be honest, I never believed it because I couldn't see how flowers would make it less stingy! But now I know.