I'm less concerned with the allegations of copyright trolling, etc (IANAL; I don't really know whether or not this qualifies for a DMCA takedown notice, although I suspect it does not) and more with the general opinion among commentators here that this was anything OTHER than a blatant ripoff of LayerVault's UI.
To me it seems like more of a trademark/trade dress issue, which as far as I know doesn't fall under copyright, but it's extremely silly to say that the resemblance between FlatUI and LayerVault isn't uncanny.
Ripping off someone's design isn't grounds for a DMCA takedown notice unless you actually violate copyright(the legal definition, not some hand wavy "I did it first" definition). If LV had filed a trademark claim no one would be complaining b/c A) they would definitely lose(there's no issue of brand confusion here) and B) the guy would get to decide himself whether he wanted to risk leaving his stuff online (instead of github deciding for him).
One of problems with copyright is that the statute basically says you can't copy original works under certain conditions, but it doesn't define what constitutes copying. As far as I can figure out (IANAL) only a judge or jury can make that determination. You can try to figure out what has been considered copying by reading through other cases but it is not definitive until declared so by a court.
To me it seems like more of a trademark/trade dress issue, which as far as I know doesn't fall under copyright, but it's extremely silly to say that the resemblance between FlatUI and LayerVault isn't uncanny.