Unfortunately I don't recall what the flowers are like, except that I thought them insignificant by comparison to the plants. Some of the other succulents are flowering at the moment, so I'll have a look tomorrow (it's now night time) to see if there are any in bloom - I don't think so, though; I seem to remember they flowered in the summer.
That said, I've looked through all 19 varieties of graptopetalum listed on Wikipedia and none seems to be a match...
