Safari 5 gained official support for extensions just last week, and developers wasted no time in releasing all manner of enhancements. Apple announced at Safari's release that it would open a Safari Extensions Gallery later this summer, and the doors are now open for submissions.
Apple's Safari Developer Program site is to place to go to submit your extensions. As we've mentioned before, developers can apply to this program for free (no $99-per-year fee like for the App Store), though they must register for a digital certificate from Apple to distribute with their extensions. The certificate serves as a failsafe Apple can in theory use to disable an extension in the eventuality that it violates Apple's terms and conditions.
We've already seen a number of Safari Extensions hit the Web, such as the LittleSnapper Extension for saving Web pages to Realmac Software's LittleSnapper design utility and a demo of Coda Notes, a Web annotation tool from the venerable Panic software shop (which is not yet available for download). An unofficial Safari Extensions blog has even been collecting extensions until Apple opens its own gallery.
Though Apple is now accepting developer submissions for the Safari Extensions gallery, there is no new word on when said gallery will be available for Safari users to browse. We also don't know how much Apple will be curating the gallery, which could continue to leave room for third parties to collect extensions that don't make it into Apple's showcase.