For those that don't yet know, "ad hoc" refers to local wireless play while "infrastructure" refers to (officially supported) online play.
Anyway, on the back of the boxes for Ridge Racer and Darkstalkers, it says "Wi-Fi compatible (ad hoc/infrastructure)." From the instructions, as well as available internet information, it does not appear that either game offers infrastructure play.
According to people on Gamespot forums, a namco representative has said the RR has infrastructure, but not online multiplayer with more info to come later. It is speculated that this could refer to online scoreboards or downloadable content.
Just wanted to warn people, and see if anyone on here had any additional information.
And I got all excited on the ride back from BB when I saw the back of that Darkstalkers box, too.
EDIT: As noted below, my initial understanding was incorrect. The term "infrastructure," is being used to refer to wireless LAN play in addition to online play.