The Green Party of California (GPCA) takes positions on statewide propositions in each election cycle. Generally the GPCA either takes a position of 'support', 'oppose', 'no position' or simply makes no recommendation, based upon achieving an 80% vote by statewide General Assembly delegates.
For the June 2012 primary, there are two measures on the ballot - Propositions 28 and 29. In considering these measures, no position gained 80% of the vote and therefore the GPCA did not take a formal position on either.
However, some county Green Parties have taken formal positions of their own. Alameda County's Green voter guide recommended 'yes with reservations' on 28 and 'no' on 29. San Diego County's Green voter guide recommended 'no' on 28 and 'yes' on 29.
For a record of the GPCA's positions on propositions in previous elections since the party achieved ballot status in 1992, see the propositions archive here.