Maybe it's just in my circles like this, but I think these days chat itself is no service anymore. You need to integrate it into something else, like social networks, gtalk, skype (chat+telephone), "webcam-services". 10 years ago Grove might've been awesome, but now it feels like something is missing, because I can chat everywhere else contextrelated anyway.

Look how meebo developed over the last years. First it integrated web and traditional chat media like ICQ, MSN and then they already moved on to integrate their chat services into other peoples web-businessmodels as a b2b service.