This year's Clydesdale Bank 40 finalists Surrey and Somerset will go head to head again in next season's group stage.
The duo, who fought out Saturday's final won by Surrey at Lord's, have been drawn together in Group B.
With beaten semi-finalists Durham also in the pool, Group B looks the toughest of the three groups of seven.
It also features a new name in the form of the Welsh Dragons, essentially Glamorgan, who have rebranded themselves in the one-day formats for 2012.
The second of this season's losing semi-finalists, Sussex, are in Group C, along with the 2010 winners Warwickshire.
Group A includes Middlesex, who narrowly missed out on a last-four place this season, Lancashire and one-day specialists Essex.
Only the top team in each group qualifies for the semi-finals, plus the best runner-up from the three groups.