I have recently become a serious Twitter addict; I started using Twitter heavily out of an interest in connecting with potential employers and developing an understanding of how Twitter works, so I can more effectively advise my B2B clients.
There are so many myths surrounding Twitter--that it's a time waster, that people only talk about mundane things like what they ate for lunch or how their afternoon dentist appointment went. While Twitter is a free communications vehicle open to everyone (so, yes, you do see conversations like that), businesses have also jumped on the Twitter bandwagon and are using it as an effective public relations, advertising and customer service tool.
Read What Twitter Can Do for Your Business (great article for those unfamiliar with how Twitter can benefit them!).