When Party Mode is enabled, all photos taken through the Google+ mobile app will automatically upload to Google+ and be shared with everyone else at the event.
That means that everyone attending your party physically, or even not physically that is invited, gets to see all the photos taken from all users that took photos all night long. That is pretty darn awesome really. Beats following a few people and having to be linked to the images they took and looking through them. This also works with any videos they take during the event. You will have access to view all the photos in a slide show format if you choose or pics added by a certain users.
To add to the glory of Part Mode, Google will take all the photos uploaded and organize them in chronological order. Photos with the Most +1′s will end up hitting a “best of” category for you to check out.
Oh and you are all invited to join the after hours party tonight with Google. How sweet is that?
Minor info from Digital Trends