Back in 12-23-2011, the Calguns Foundation (CGF) filed a lawsuit (Silvester v. Harris) challenging CA's 10 day waiting period.

Today (12-09-2013), Senior Federal District Judge Anthony Ishii dismissed CA Attorney General Kamala Harris’ Motion to Dismiss the lawsuit.

Quote Originally Posted by Judge Anthony Ishii
The waiting period law (WPL) as applied against those who have previously purchased firearms or who possess certain state licenses is the equivalent of a prior restraint, and thus should be analyzed under strict scrutiny. However, under either strict scrutiny or intermediate scrutiny, the [10-day waiting period] fails. In terms of strict scrutiny, Harris has not shown that the law is effective either in reducing gun violence or in keeping firearms out of the hands of unqualified purchasers where the government has already issued that purchaser a License To Carry or a Certificate Of Eligibility.

In terms of intermediate scrutiny, neither of the bases argued by Harris is sufficient. There is no indication that the WPL is necessary to weed out unqualified purchasers. While it is appropriate to have a background check, the current systems and data available do not make the 10-day waiting period reasonable. In terms of cooling-off, there is no evidence to support the efficacy of the law in preventing impulsive firearm violence. Moreover, for those who already legally possess firearms, the WPL would have no effect in terms of creating a “cooling off” period. Any spontaneous desire to perform a violent act can be manifested through the weapon that is already in the individual’s possession. Because the WPL fails intermediate and strict scrutiny, Harris’s motion must be denied.
This is the first battle in the war against CA's waiting period law and it's a win.

This lawsuit may lead to a ruling in which non-prohibited persons that have a CA License to Carry permit or a CA DOJ BOF Certificate of Eligibility or a CA DOJ BOF Dangerous Weapons Permit to be exempt from the waiting period.

Best case scenario, it may also lead to a ruling that waiting periods are unconstitutional and the waiting period laws are voided/stuck down.

Keep in mind this is just the first battle in a long war.