The attribute editor in Maya 2012 keeps expanding the Notes roll-out. I'd never noticed this being quite so annoying in previous versions. I'm pretty sure that previously, once I closed it by dragging the divider bar to the bottom of the window, it stayed like that until I pulled it up again. Now, in maya 2012 it seems to jump up again as soon as I deselect anything. Most of the time this is a waste of space for me.
Fortunately I recently read a simple solution posted on cgtalk by ginodauri. To hide the notes roll-out you can use the following mel command
layout -e -vis 0 AEaddOrEditNotesLayout;
To make this even easier I thought it would be good to add a menu item to the List menu in the attribute editor.
So you can turn it on and off and maya remembers your last choice between sessions.
This functionality is added by modifying a copy of one of the maya installation files called showEditor.mel which can be placed in your local scripts folder to avoid messing up the maya install. You can get the mod for maya 2012 from my downloads page.
update: added 2013 version