Another day, another tablet. But this one has the potential to really sell. Research in Motion, the makers of BlackBerry smartphones, have just unveiled their long-rumoured PlayBook, the tablet PC for the BlackBerry user (at least, that's what they're hoping). Billed as 'the first tablet for business,' it's a 7-incher like the Samsung Galaxy Tab, with a 1GHz A9 processor and 1GB of RAM. Standard tablet stuff - but unlike the Galaxy or iPad, it runs BlackBerry's own OS, in special tablet version. That means rock-solid email support, and slick multi-tasking. We don't see this becoming a favourite for regular folks, but RIM will be hoping it'll do well with the commuter brigade. No word yet on when it'll be with us, or for how much.