As pointed out by our sister site, MacRumors, Business Insider's Jay Yarow snapped a photo of what very likely is a banner for iOS 8. Apple typically reveals new operating system details at WWDC, as it's a developer-oriented event, and it'd make a lot of sense for iOS 8 to take up a major portion of the keynote. (Which Apple is streaming live!)
It's anyone's guess what iOS 8 could include, there's always some new killer features, but I'd be really happy if they expanded Game Center. Apple's online leaderboard service has been super light on its feature set since it launched, and it'd be really sweet if they brought it more in line with what people expect of these kind of things. If nothing else, I'd love to be able to message my Game Center friends without revealing my iMessage ID or phone number.
Either way, we'll find everything out on Monday, so stay tuned.