Maria Shriver, Arnold Schwarzenegger headline a celebrity divorce-o-rama

A gaggle of on-the-rocks celebrity couples followed the leak-bad-news-before-a-long-weekend playbook Friday (July), with not one, not two, but four divorce announcements hitting the web late in the day.

The biggest one is Maria Shriver filing for divorce from Arnold Schwarzenegger after 25 years of marriage. TMZ reports that Shriver, who separated from the action star/ex-California governor earlier this year, cites the catch-all "irreconcilable differences" in court papers.

Given the revelations of recent months that Schwarzenegger fathered a child with the housekeeper, it's not a huge surprise. Shriver is asking for spousal support, joint custody of their two teenage sons and attorneys' fees. The couple didn't sign a pre-nuptial agreement, so their assets will be split equally.

Things were busy in the L.A. Superior Court Friday, as three other celeb couples got the final word on the end of their marriages. Per TMZ:

- Scarlett Johansson and Ryan Reynolds filed their final divorce papers. It went amicably: Neither party asked for spousal support, and they're splitting what they earned during their two-year marriage.

- Patricia Arquette and Thomas Jane are also done. Arquette initially filed for divorce in early 2009, but the couple reconciled for a time. They split again 11 months ago, and now their divorce is final; they'll share custody of their 8-year-old daughter, Harlow.

- Finally, George Lopez and his wife of 17 years, Ann Serrano, finalized their divorce Friday. She filed in November.