That's the icon for the del.icio.us bookmarking service. If you click on it -and are logged into del.icio.us- you can save the URL on that site.
I'd urge anyone who hasn't done so to check out del.icio.us; I think it's cool (and it's widely used all over the web, so you'll see this icon in lots of places). [ November 10, 2008: Message edited by: Ulf Dittmer ]
Ping & DNS - updated with new look and Ping home screen widget