Doesn't seem to be the case... Here is mini datasheet for the H&D module used on the shield:http://media.digikey.com/PDF/Data%20Sheets/H&D%20Wireless%20PDFs/HDG104_Product_Brief.pdfIn your specific case, why not the alternative of setting up a network on the computer's end, and connecting to it from the Wifi shield?
If I understand you correctly you want:1. A WiFi shield to automatically detect networks within range and then select one to connect to automatically ?2. Then you want the user to turn on their computer and be able to select the service the Arduino/WiFishield offers ?1.) that can be down, however, of course this would only work for open networks. And of course you don't know what network your user sits on. Perhaps you need to study the general workings TCP/IP networking a little bit more before giving up on the project. You can run some WiFi shield in AP (Access Point) mode. that way they create their os network the user then can connect to. Or you have it connect to the users existing network. If it's a closed network the Arduino/WiFi shield will have to provide some form of authentication via passphrase/password to be able to log into the network.2.) Sure, that technology os called ZeroConf with the most prominent implementation being Apple's Bonjour. There are libraries for Arduino that help you do that like DHCP, Bonjour libraries etc.Having said all that. Nothing happens by itself magically. You'll have to write software to do it
Ad hoc and infrastructure modes are incompatible, meaning you cannot connect a WiFi shield Lin ad hoc mode to an Access Point (infrastructure mode).When you are scanning you are likely scanning for infrastructure mode networks or in other words for APs within range. Most WiFi networks are operated in infrastructure mode.From your description I am gathering that you want to provide your user with comfort functions similar to connecting your iPhone ( or Android phone) to a given WiFi network. On an iOS device you go into "Settings -> WiFi" and ther are you presented with a list of available WiFi networks that you could connect to. What you are seeing in that in that list are Access points.Then you want the user to select which network to connect to and depending on that networks settings provide a password.Once you are connected to a network, provided these devices Support Bonjour, you can see what services are offered and other devices can see what services are bing offered by your device.I am, not sure that can be easily done with any WiFi shield as the Arduino DHCP/Bonjour libraries depend on the Arduino Ethernet library and thus you need an Arduino Ethernet shield. But you can easily connect a little pocket router, e.g. A TP Link TP 702 router?However I am sure that soon the newly released Arduino WiFi shield will provide a lot of functionality that was previously not available.