8.1, not the dreaded Windows RT. This is most likely because Dell has been targeting enterprise users, but the Venue is expected to be aimed at the consumer market as well.Originally, the Dell Venue Pro was a Windows Phone smartphone with a slider keyboard, but this time around the Venue brand is being used on a Windows tablet. Dell has been active with Windows 8 hybrid devices, and it does still have a couple tablets on the market - the Windows RT XPS 10 tablet, and the Windows 8 Latitude 10 - but the Venue will be used on a smaller Windows tablet. The new Dell Venue will be an 8-inch tablet that runs full Windows
The Venue will have a 1080p display, an Intel Atom Bay Trail processor, HDMI out, and microSD card slot. Otherwise, we don't know what to expect. Dell is planning to announce more info on October 2nd.
source: The Verge