Yes, there's a column of varchar(300) there somewhere. Sorry we didn't catch that bug, because on our environments it didn't throw an error.
To fix it go to /public/install/installation/templates/sql/mysql_schema.php and change line 666 (funny huh?) from this:
`description` varchar(300) <?php echo $default_collation ?> NOT NULL default '',
to this:
`description` text <?php echo $default_collation ?> NOT NULL default '',
I will update the installation zip file.
Thanks for reporting the bug!