I hate it.
When I'm working, there's nothing more annoying than the little box that suddenly pops up on my screen, complete with alert sounds, demanding my attention like a 2-year-old. (Yes, I know I can ignore it and it will go away, like letting calls go to voicemail.)
Maybe it's because as a writer I like to plan out my words...but I really hate chat. (And it cuts into online dating, too, since everyone else seems to take it as a given that everyone loves chat.)
Anyone else hate chat? Don't get me wrong--I'll do it, since many clients love skype and other chat platforms. But I strongly prefer email and phone. Maybe it's an age thing.