The exciting part about OpenMeta is that developers finally have a standardized way to assign and read tags on files (other than the less-than-ideal Spotlight comment hack of yore) which has the potential to free users from getting tied down to a particular solution. Aside from Tags and Deep (the first of which is compatible with OpenMeta, the second of which was the first program to use it), MailTags is also in the process of joining the OpenMeta bandwagon (not available in public builds yet, unfortunately). Hopefully software like Together, EagleFiler, and others of that ilk will also begin to incorporate OpenMeta, allowing users to tag and find files across the system and their various tagging programs without needing to keep all of those programs running.

If you yourself are interested in taking a peek at the source code, it is freely available from the BlackTree Google Code site. The current BlackTree release of Quicksilver remains a beta, although it has been updated for 10.5.