I haven't seen the clause in question, so I can only offer some general information.  Generally, such clauses are enforceable in MA if they are necessary to protect some legitimate business interest of the employer (such as trade secrets, client lists, etc.), do not violate some public interest or policy, and are reasonable in time and scope (both in terms of what they prohibit and over what geographical area).  Early in 2009, a bill was introduced to make non compete agreements unenforceable in Massachusetts (in certain, limited situations).  You can read the bill here.  However, as of this date, non compete agreements are still enforceable in Massachusetts. 
 
You don't talk about why this clause is of interest to you, but an employment contract is like any other:  You can attempt to negotiate any clause in or out of the final agreement.  Depending on your reasons for not wanting the clause in question, and on how much they want you, they may agree.  You may also want to have the contract looked at by a Massachusetts employment law attorney, especially since there is some legislation pending which may impact this issue.  Good luck.