There's a lot of sneering about Twitter. Not sure why.
Academics have taken to Twitter in a big way. One of the most important aspects of it is the exchange of information; another is that its informality and scope makes it easier for researchers (particularly younger ones) to make contact with colleagues. I've seen cross-discipline collaborations set up over Twitter between researchers who hadn't met and who probably wouldn't have met otherwise because their main interests were different. I haven't noticed many cat photos, but I have seen some excellent photos of frogs, deep sea invertebrates and insects from the Amazonian jungle. No discussions of dinner. But if I wanted those, I could look in at the Holiday forum.
This article (from a tweeted link) looks at a handful of stats and makes some observations about the way academics use Twitter. (Apart from the reasons in the cartoon at the start.)