The good people at Griffin Technology have released a new beta version of the iMate driver for Mac OS X. The new release includes performance enhancement and support for more ADB devices on a single chain. According to Griffin Technology:
Griffin Technology, Inc. posted a new beta version of their OS X driver for their popular iMate USB to ADB adapter. Version 1.0b5 of the driver has several performance improvements, bug fixes, and enhancements. The new version improves performance by speeding up ADB polling as well as other driver optimizations. It also supports more ADB devices. You can now connect as many as 15 ADB devices to a single iMate under OS X. Additionally the driver is now far more reliable with multiple ADB devices connected.
The iMate OS X driver is compatible with all currently available ADB drivers including the Kensington Mouseworks driver and the built in OS X ADB drivers. The iMate is fully hot pluggable and can support custom ADB drivers even if the ADB devices were not connected during startup as would be required with built in ADB under OS X or with ADB under OS 9.
You can find more information and download links for the drivers at Griffin Technologyis Web site.