California has long had a statute making employment related noncompetition agreements illegal. There has been for some time now in Massachusetts a movement to make these agreements illegal here as well. An article in xconomy has this to say on the subject:

The alliance, founded last year by partners at Boston’s Spark Capital, argues that the non-compete clauses imposed by many Massachusetts employers stifle innovation by preventing entrepreneurs with good ideas from setting up new businesses that might be seen as competing with those of their former employers. Such agreements are unenforceable in California—a fact that may aggravate brain drain from New England to the West Coast, in the view of many people active in the local entrepreneurial scene.

Noncompetition agreements are also a topic on which Mike Rosen, one of my partners, writes with some frequency. 

I don’t have an opinion whether these agreements actually stifle innovation nor do I know how such a thing would be measured. I can safely say that I have not heard anyone make the case with any conviction that noncompetes promote innovation by protecting investment in new companies. But, noncompetes are a “standard” part of the employee package at any venture funded company here in Massachusetts. They are typically (universally ?) one year agreements – in the venture funded world. Once you get outside the venture funded world they get longer and longer. I have seen employers ask for as much as five (count them – five) years.

Having said all this, there are other agreements that are part of the “standard” package including, for example, non-solicitation of employees, non-hire provisions and non-solicit of customers. My understanding is that these provisions are just as legal in California as they are in Massachusetts. Employers can get much (most? all?) of what they might in a noncomp from these provisions. If you agree with that last sentence, it is going to be really hard to determine what, if any, benefit there will be from making noncompete’s illegal.