AT&T has an extensive network of WiFi hot spots in places like McDonald's all over the country. If you have an AT&T account for your iPhone or iPad, you can use these hot spots for free (and in McDonald's they're free for everyone). This wasn't always the case – but as AT&T saw how overwhelmed their cell data network was, they decided it might be a good idea to open up their WiFi network to take the load off their cell cloud.
Don't be fooled by the siren song of WiFi, however, especially when buying an iPad, If you think you'll travel a lot (at least in the US) with one, consider very carefully whether or not to buy a 3G model. I'm glad I have the 3G and not WiFi only.
On a recent trip to Lancaster, Pennsylvania, I stopped several times at places with free WiFi, some of them AT&T's WiFi at McDonald's, some at other places, like Panera Bread, that had non-AT&T free WiFi. However, for some reason they blocked IMAP port 993 – the port you're supposed to use for encrypted iMAP email. You can also use port 143, but I shouldn't need to reconfigure my device from a simple standard like the IMAP encrypted port. Why on earth that was blocked I'll never know, but I think it did me a favor. I decided to use the WiFi for web browsing, and it was excruciatingly slow – so slow that I switched back to 3G data (figuring if it was going to be slow I might as well get mail too) and got a huge speed increase!
What was also annoying was my standard trick for getting around silly firewall rules like that one is to open a VPN connection to my server. But the VPN ports were blocked too!
The hotel was a joke as well – I heard a rumor that they were set up for 250 people on their wireless network. I don't know if it was true or not, but there were over 1500 people at this convention, and many of them had laptops and smart phones. I do know that when I got a signal, I frequently couldn't get an IP address for 10-20 minutes at a time (and sometimes I just gave up after 20 minutes). This wasn't a problem for my iPhone and iPad – I left them on 3G data. But my MacBook Pro only has WiFi. I only really needed the MBP for a few emails (with PDFs that the iPad/iPhone won't display correctly) and to connect into work (it's easier to remote control the programs I need to run with a real mouse). At least the VPN worked at the hotel (when I could get a signal and an IP address, which was usually very late or very early in the morning), because they too blocked port 993.
So before you think you can travel with your iPad and won't need 3G data, you might want to think again. WiFi done poorly is much worse than 3G data!
Anybody else finding that their actually better of on the overloaded 3G network rather than public WiFi?