Macs are actually pretty "smart" where wireless stuff is concerned. I *think* if you have a wireless card, then you can pretty much connect to any open network. My Mac (ibook G4) will automatically find any open networks.
If you already have the airport installed in your computer, you will be able to pick up a wireless signal anywhere you go where there is one. Once I open my iBook, it just asks me 'connect to _________?' and when I click 'yes' it connects for me. Very easy!