Expert Sleepers has released Augustus Loop v2.2.0 - a 64-bit update to their "virtual tape" looper.
Augustus Loop is now a 32/64 bit Intel Audio Unit, and can be used in native 64 bit mode in Logic 9 and Mainstage 2.1 when those hosts are running as 64 bit applications.
Expert Sleepers notes, "From now on we anticipate that all our Mac releases will be Intel only, will support 64 bit use, and will require Mac OS X 10.5 or 10.6."
This update is for 64-bit support only. If you're not running 64-bit apps, there's no need to upgrade.