Avid has announced support for Mac OS X Lion version 10.7 with Pro Tools and Pro Tools HD 9.0.5 BETA software.
Full qualification of this new OS is expected at a later time.
Avid notes that Pro Tools beta software will contain minor bugs and issues, adding that in most cases, this will not impact usability and performance. As a result, the company recommends that users in “mission critical” applications do not use Lion and Pro Tools 9.0.5, and remain on a fully qualified platform.
Snow Leopard and Windows OS support: Pro Tools 9.0.5 is fully qualified to work with OS X 10.6.x (Snow Leopard) and Windows 7.
Go here to find out system requirements, and go here for the latest information about requirements, open issues and caveats in tandem with Lion OS.