Adobe emphasizes that Square is designed to take advantage of IE9's hardware accelerated graphics; the software company is claiming performance increases of up to 35 percent in IE9 "compared to previous versions of IE." That's quite a big jump, but we must remember that the number is comparing against old 32-bit versions of IE, so the gain is a combination of the improvements made in IE9 plus the enhancements of the 64-bit Flash player.
In addition to performance, we're hoping the 64-bit plug-in brings security improvements, as Adobe Flash is full of holes. The company warns its users that the release is meant for testing existing content and new platforms for compatibility, so don't expect much stability and use caution when installing Square on production machines.
You can download Square Preview 1 from Adobe Labs. Adobe said its latest Flash player is expected to ship in the first half of next year.