Dell is leaking a new Dell Inspiron Mini netbook themselves on their support site. Update: Dell Mini 12 officially announced, runs Vista.

The new Dell mini is dubbed Inspiron Mini 12 (1210) and will actually feature a 12 inch screen, the largest in an Intel Atom powered Netbook to date.
Other features of the Dell Mini 12 include Intel Atom Z520 or Z530 CPU, 1GB RAM, 1.3MP Camera, Wifi, and Bluetooth.
Now that the support documents are already live for the Mini 12, it should not be long before Dell officially announce their new 12 inch netbook. Currently Dells sells the Dell Mini 9.
More details on the Dell Support site. Via Engadget and CMS Report