I don't use Facebook (just LinkedIn) but I took a moment to read the explanation and find it "a bridge too far". Perhaps, if used sparsely it could have its charm but 80% of the uses would be useless :-)
I don't think it's necessary, but I wouldn't hate it either. I never used the poke function on Facebook. A friend used it once, and all we ended up doing is keep on "poking" at each other until it got annoying.
I think the option to "tag" someone would be more useful.