For our new Dayton Oracle SIG, we want to run interactive, laboratory-style meetings. We'll meet in a place with wireless, one member will bring a laptop running an Oracle server and Oracle Application Server, and other members will use their laptops to access it and muck around.
This requires the computers using the wireless network to access not just the internet, but each other. I'd call this "peer-to-peer" networking, but it's really "peer-to-router-to-peer".
If I connect to my wireless at home and issue
ifconfig, it reports eth1 ... inet addr:192.168.1.45. For other machines connected to the same router, that IP address is as usable as anything on the internet. If Oracle and Apache are running on the machine, I can use 192.168.1.45:1521 and 192.168.1.45:80 to log into the database or view webpages from other machines. If I go into my router and set Port Forwarding to ship incoming traffic to 192.168.1.45, then those become visible to the wider internet... but, to access them within the wireless network, I don't even need to do that. (In fact, I don't see any way I could turn it off even if I wanted to.)
So all we need is a meeting location that allows the same thing. It's not that simple, though. As far as I can tell, the wireless at Panera Bread (my first choice) doesn't permit this kind of inter-machine connection. That locally assigned IP address doesn't produce any response from other machines in the same network; it seems the router simply doesn't route traffic between machines. For security's sake, that kind of makes sense; I wouldn't want somebody hacking my database from the next table over. (Actually, if they did, I'd invite them to the SIG, but that's me.) But it removes some really neat possibilities for interaction.
I've found one place so far - the Hope Hotel in Fairborn - where the wireless does allow connections between machines. I was all ready to declare the hotel restaurant our meeting location, until my boss reminded me that it's full of GIANT TELEVISION SCREENS BLARING SPORTS and some people don't tune that out as automatically as I do.
I suppose there's always the option of bringing a router with me... but then I'd have to bridge people's traffic up to the internet somehow. I'm sure it can be done, it's just something I've never developed the skills for, nor do I own a particularly portable router. Hmm...