We’ve mentioned Square, the new tool for accepting card payments on your iPhone (and iPod, iPad and Android mobile, actually), a few times in the past few months, most recently yesterday as an aside to the news that another ex-Twitter employee has quit to go and start an innovative new bank.
If you’d like to learn more about Square, there are a few videos on Youtube that explain more.
The first two are from Square themselves:
And here’s a Square demo by Kevin Rose, founder of bookmarking site Digg: