Playing iTunes from 2 computers simultaneously??

Hello all... I have an iMac and MacBook pro. I have my library on both machines. Keeping it current is a topic for another thread. But what I was wondering is... Is there a way to have both playing the same song simultaneously? I want to have both machines playing so I can keep my iMac in the basement, then bring my MBP upstairs with me. What if I access my iMac's library from my MBP via iTunes shared library? Or something like that??
Thoughts??

[By the way, I searched for hours and didnt see anything quite like this. I noticed other posts about keeping libraries synced but nothing about playing in both.]

Thanks!

 

I have 2 airport expresses that Im using to stream to other speakers, but can I use it with another computer?? If so, how??

If I could simply select "MacBook Pro" from my list of airtunes speakers, that would be the ideal setup.

 

EXACTLY WHAT I WAS LOOKING FOR. Thanks noni!!