I didn't see an easy way to access or alter the comments of a column's comments.
in SQL, to set the comments:
ALTER TABLE `user` CHANGE `id` `id` INT( 11 ) COMMENT 'id of user'
And to retrieve that data:
SHOW COLUMNS FROM `user`
Is this possible with RedBean? (aside from using $rb->getAll($query...) )
Some of the uses that come to mind include text labels for input fields, and metadata related to that field that applies to all of -x- objects of that type/table, like the fact a column might be depreciated, or that field is used by some other app with it's own connection to the database.