Q: Dual 27" LED's, can the speakers work in stereo?

this is very easy to do.

open 'audio midi setup' in utilities.

click the plus in the lower left and add new aggregate device

check both display audio's

hit configure speakers in the lower right

check both checkboxes at top.

choose mutichannel & quadraphonic.

then you can click each one and test the sound.

hit apply and done

then right click on the aggregate device listed in the left you just created, click on use this device for sound output and player alerts and sound effects through this device

and you should be all set!!1 i had to configure levels on my displays, they were set differently.  You can play with this (which i recommend) but clickin the triangle next to the aggregate device

click on the the first display audio and then on top click output and choose your levels.

do the same for the second display audio.

GOOD Luck

Brad, what would you think about doing this with a pair of soundsticks coupled with two cinema displays and the iMac's display? 

It would work, the built in speakers ovbiously aren't gonna be as good but you could lower the volume on them and use them as tweeters almost. Might be cool.

Give it a shot!!

Thanks Brad. Great instructions. Worked perfectly for a Apple Cinema 27" and an iMac.