A number of official Apple iOS apps are now "optimized for iPhone 6," whatever that may mean. iMovie, iPhoto, Pages, Keynote, and others now include that text in their web description on iTunes in the compatibility section. Some third-party apps also include the string of text, which reads, in full: "This app is optimized for iPhone 6." It's important to note that it's very possible that the message is merely an odd mistake that's not indicative of Apple's plans, but we'll know for sure on Tuesday at the company's press conference.
Rumors and leaks have long suggested that Apple will unveil the iPhone 5S, a modest upgrade to the outgoing iPhone 5, as well as a less-expensive iPhone 5C in a number of different colors. The last time apps had specific "optimization" for a particular iPhone was with the 5, which introduced a larger 4-inch screen that required developers to tweak their applications for proper support. It's said that Apple has considered making an iPhone with screen sizes up to six inches, but rumors say that if such a device were ever to come out, it'd be some time next year. It's also unlikely that a larger iPhone would carry the iPhone 6 moniker. We've reached out to Apple for comment, and we'll update this article accordingly.
Follow along: our liveblog of Apple's iPhone event
After the event: Join us for The Verge Live
Update: It appears the note is likely the result of some sort of error. As commenter omen87 notes, iMovie pages in the app store show different messages depending on region. It looks as if all Canadian iTunes web links include the iPhone 6 text, while the US link says "optimized for iPhone 5" and the app page says "optimized for iPhone 7" in New Zealand, for instance.
Update 2: The text has now been removed from the links in question, and replaced with "optimized for iPhone 5." Apple couldn't be reached for comment on the iPhone 6 reference.