The article from Microsoft I read, maps out the usage and purpose of the Ad Hoc. It encourages multiple connections with no mention of limitation.
Ad hoc networking - Windows Vista Help
--------------------- Notice the use of plural in bold below, suggesting multiple connections ------------
Tell your friends
If you saved your ad hoc network and you want your friends to connect to it (to play those games!), here's how they can do it:
1. Click the Start button , click Connect To, click the network you want to join, and then click Connect.
2. On the Successfully connected to <network name> page, if you want to connect to this network again later, click the Save this network check box, and then click Close. (Ad hoc networks normally disappear after you disconnect from them.)
3. On the Select a location for the <network name> network page, click Home or Work. This will automatically turn on network discovery and file sharing.
4. On the Successfully set network settings page,
click View computers and devices on the network.
5. To find a file that is shared on another computer, double-click that computer's name in the list, double-click the Public folder, and then double-click Public documents. Depending on the file permissions, you can read, edit, copy, or print the file.
6. When you're done using the ad hoc network, just disconnect and it will disappear (unless you selected the Save this network check box previously).
Note If you're trying to view files on a computer that is joined to a domain, you must have either a domain user account on that computer or a local account on that computer.