I am one of Ektron's customers awaiting this fix.
I've managed to force-install the plugin in FF3.5, and the control (a rich editor) does appear to load fine. However something is still amiss in that the control does not store any data entered. Perhaps it's some piece of server interaction.
I can provide screenshots on demand of the control working in 3.0 and failing in 3.5.
Doug - thanks for your request to Esker. I know you always do what you can for your customers. I'll be keeping up with the progress of this post. Hopefully we'll see a rapid response.
Regards,
James Stout
Lead Web Designer
King's Daughters Medical Center