Square's been one of my favourite party tricks - watch me take your money with my iPhone! - but now everybody can join in with the full release of the apps for iPhone, Android and iPad. Which is actually more exciting.
Noah at Fast Company lays out pretty much everything you need to know about Square - founded by Jack Dorsey, one of the Twitter guys - and why the simple ability for anybody to take credit card payments is so potentially awesome. (Also, check out Wired's cover story from the other month on the future of payment systems for some big picture perspective.)
The receipts are neat, BTW, with geotagging and stuff:
Or you know, just sign up for Square, since it's free, and start messing with it yourself. [Square]