A new version of the OrbAddOnManager executable has been released.
If you are developing add-ons using Orb v551+, you must use this new exe.
This new version also adds support for the soon to be released Add-Ons API v2.0.
Orb Add-Ons API 1.0 has been released.
You will find here the headers to use it and the source code of some addons (including Bookmarks which is distributed with Orb Media).
Documentation available here: http://www.orb.com/download/add-ons/api/doc/index.html
A forum for developers is available here: http://forums.orb.com/community/viewforum.php?f=20
More details here: http://www.orb.com/download/api/download/