I just downloaded the Enhanced Gmail Plugin after reinitializing my 5 gmail accounts.
It seems pretty cool but I can only use the advanced features if I go into the mailbox icon for each gmail account. For example, I can't use the unified mailbox to use the advanced features.
It seems this is by design:
"Note: Google Mail enhanced features are only available within the Enhanced Google Mail plug-in and are not available when viewing Google Mail messages in the Messages application on the BlackBerry smartphone.
This makes it almost useless for me as I don't want to have to click one of five email folders everytime I want to read a message.
Still some great new functionality though if you don't mind clicking into the mailbox. The threaded view and remote search is SWEET!
Here is the link to info about the plugin:
Introducing Enhanced Google Mailâxxx8222;˘ plug-in for BlackBerryÂ® smartphones - Announcements - BlackBerry Support Community Forums