Two polls were actually released today on the 2010 California Governor's race. The Field Poll did an extensive poll of the race, including favorability ratings, and Lake Research, a Democratic firm, did their own poll which included some head-to-head matchups.
Field's poll included Dianne Feinstein and I don't think the results were all that great for her. In the primary she polls well under 50%, compared to earlier polls which had her closer to that number.
Dianne Feinstein: 38%
Jerry Brown: 16%
Antonio Villaraigosa: 16%
Gavin Newsom: 10%
John Garamendi: 4%
Steve Westly: 2%
Bill Lockyer: 1%
Jack O'Connell: 1%
Undecided: 12%
Considering she's the most well-known figure in California politics, and that there won't be that many competitors in the final field, that's not a runaway at all.