Apple Messages, the iChat replacement that integrates cross-platform text, video and photo messaging between Mac and iOS, will only be available for OS X Lion users until Mountain Lion is released this summer it's suggested. Having previewed Mountain Lion, Apple released the Messages beta yesterday for those with Macs running Lion to try the software out. However, according to Consomac's digging, the beta will only be valid until Mountain Lion's release, at which point users will apparently have to upgrade if they want to continue chatting.
The revelation comes from text strings unearthed within the Messages beta's own resources, in the form of a warning message presumably intended to be shown toward the end of the test program. "Thank you for participating in the Messages Beta program. With the inclusion of Messages in OS X Mountain Lion, the Messages Beta program has ended" the notification says, "To continue using Messages, please visit the Mac App Store and purchase OS X Mountain Lion."
Mountain Lion is to be a paid upgrade, Apple has confirmed, though the exact price is still to be revealed. OS X Lion was a $29.99 upgrade from the Mac App Store, however, so we're expecting something along the same lines.
What happens to those users who opt not to upgrade from Lion - or, indeed, have Macs that are unable to run the new OS - is unclear. One possibility is that, like FaceTime before it, Apple will release a paid Lion version for a nominal fee; FaceTime for Snow Leopard users was $0.99 when it hit the Mac App Store, because Apple was constrained by the Sarbanes–Oxley Act of 2002 and couldn't give the functionality away free.
We've got a request in for more information from Apple on what will happen with Messages, and will update when we hear back.