Heads-up, BB10 users -- checking in just got a little less second-class. Foursquare has today issued an update to its BlackBerry 10 app that effectively brings it closer in line with the version already available for iOS users. For starters, there's a more compact Explore screen, and your friends can now be tagged in check-ins and comments. For big spenders (or frugal ones, we guess), Visa and MasterCard specials can now be taken advantage of by Z10 users. Per usual, i
