Community member Kim Parsell recently emailed me a link to a post that she had found, which described the exact same problem as I was experiencing with the Filosofo comment Preview plug-in. When I tried to activate the plugin on my blog, I got an error similar:
Call to undefined function get_currentuserinfo...
As I researched the problem, I discovered that it was related to pluggable.php. I tried uploading a new pluggable.php file to a fresh WordPress.2.7 installation, but that didn’t work. I decided to leave the plugin disabled, and then went to work on it locally until Kim sent me this message.
Saphod.com publishes a block of code which you can add to the comment preview plugin which should enable both plugins to be activated at the same time. Since the site is now public, I have disabled Maintenance Mode.