[mod_python] Refresh browser's images on server's request

Hi all,
Please can someone tell me if it is possible, and if so - how, to 
refresh images in client's browser only when they change on server? I'm 
not thinking of a cache, rather imagine following: a few people are 
looking on the same web page. It has a few images. A user can change an 
image. When this happens, the others should immediately see the changes, 
e.g. their browsers have to refresh the page automatically.
Can Mod_python do this?
I will be very thankful for any help, tip, hint, example, strategy, ....
Thank you in advance.