The second part of the DOMA act, that states do not have to recognize same-sex marriages of other states, was left intact. It was the third portion (federal recognition and benefits) that was struck down. (See Wikipedia here.)
The opinion will obviously be important to military same-sex couples, and to immigration of couples from countries recognizing same-sex marriage.
Update: June 28
The Ninth Circuit has lifted the stay, and same-sex marriages can resume almost immediately in California.