Just drag the group into a Numbers document. It will only bring in basic info.
If you want more info, you can create an Automator Workflow or Service which will export the contacts to a tab-delimited file which can be opened with Numbers.
You must select all the indivdual contacts you want to include, so for a group, select the group, then select a contact, then cmd-a to select all.
The first action gets the selected contacts.
The second action gets the information you specify. Note that it is set for spreadsheet format.
The third action copies it all to the clipboard.
Paste into a Numbers Spreadsheet.
Note that there are various options on how to get the contacts. Using the selection is the most convenient as you can get any set you want.
An Automator Service will show up in the Services contextual menu, Services menu on the Application Menu, and can have a keyboard shortcut set. For a Service, it can get what you have selected, but I don't know of a way to get the contacts, so just set it to No Input in Contacts. The "Get Selected Contact Items" action will get the necessary items. You can set the shortcut in the Keyboard System preferences.
A Workflow can be run by double-clicking. It doesn't have an input like the Service.
If this is just a one-time thing, use a workflow and you don't even have to save it. Just run it and don't save it.
You will need to use a program that can import contact information, and I don't believe Numbers will do this. The Contacts program can only output as vCards or as a PDF listing, but the layout of this prevents it from being copied into a spreadsheet easily.
If you simply need a list, then perhaps the Contacts PDF option will work for you. To do this, select your group and then choose "Export as PDF" from the File menu, and you should have a formatted listing of the group's contact information.
When I drag a group from Contacts to Numbers, absolutley nothing happens. When I drag just one contact from a group into a field on a spreadsheet, again nothing happens. Are you sure this is how to get basic info into a spreadsheet in Numbers?? I tried using Automator Workflow but not sure if I chose the correct instructions! Any further help would be invaluable.