Assembly Bill 327, introduced by Assembly Member Davis, passed in the assembly today. The new bill, whose text can be found here in full, would activate the "third strike" life imprisonment provision only if the third felony is for a serious or violent felony.
What counts as "serious or violent" felony is defined in section 667.5 of the existing penal code. The category includes serious offenses like murder, attempted murder, rape and kidnapping, but also first degree burglary, extortion and the like. It would seem to exclude some of the more scandalous examples of three strikes practices, in which the third offense would be petty theft of some sort.
The bill now moves to the senate floor. But getting too excited about this may be premature; the bill explicitly specifies that it only comes into effect if approved by voters in the 2014 election.