This is the only inkling of one that I've seen, dunno how much stock to put in it. Ben Page is reliably obviously but it's secondhand info: https://twitter.com/benatipsosmori/status/745910470033432576
Yeah, there's definitely been people sniffing around wanting an exit poll, and there's been activity at polling stations, but nothing that actually looks like something that would usually be called an "Exit Poll".
Whatever, we'll know one way or the other soon enough.