Original description by David Peterson:

I am now getting a different error message, depending on what type of plugin I am installing:

1. Bundled Plugins (e.g. IM Presence NG): They download and apparently finish successfully, but the plugin is never updated.
2. Other plugins (e.g. Scaffolding, Linking, etc): They download but then come up with the following error message:

The plugin key provided is not installed:
org.randombits.confluence.scaffolding

Setup: Confluence 2.3.3 & Confluence 2.4.5, Atlassian Plugin Repository 2.0.2

http://confluence.atlassian.com/display/CONFEXT/Confluence+Repository+Client?focusedCommentId=42139690#comment-42139690

Version 2.0.3 of the repository client fixes this problem.