You can marry a same-sex partner in Massachusetts...now. That's right. Now. Governor Patrick signed the law and it contains a waiver of the usual 90-day waiting period to take effect.
If you want one less legal headache, cancel the plans for Berkeley and head to the Berkshires. Same-sex marriage is safe in Massachusetts. With California voters deciding in November whether to eliminate marriage there, the marriages performed between now and then will be under a cloud if the anti-gay forces prevail. There will continue to be issues about whether other states will recognize Massachusetts marriages, but at least you'll know Massachusetts won't pull the plug.