Three judges in California ruled that the overcrowded prisons are a public hazard and that up to 57k prisoners will be released.
According to an old LA Times article, each prisoner costs the state $31k per year.
So, reduce a public hazard and save $1.8 billion per year.
California's budget deficit for 2008 was $17 billion, so this should account for something close to a 10% reduction of the deficit in 2009.
The only downside: 57k more people looking for jobs. All of them with criminal records, few of them with any significant education or work experience.
Maybe the state could pay them $31k per year to dig ditches, provide them with a secure place to sleep, meals, time to exercise...