Scott Kelby has organized a Photowalk on August 23, 2008 in over 200 cities worldwide.
What is a Photowalk, you ask? He has a video on his website that provides all the details, but basically, you meet up with a group of people and take a somewhat planned route through an area of town, capturing as many different photos as possible.
Most groups end up at a coffee house or restaurant to ooh and ahh over each others work.