For family reasons? Yeah right - his son is in college. The real reason could either be good or bad.

Good reasons:

• He will be indicted and frog-marched to jail for one of his innumerable crimes. Marcy Wheeler thinks the most likely prosecutions involve (a) Jack Abramoff (if Susan Ralston rats on Rove), (b) violating the Hatch Act by showing his powerpoint to every federal agency, or (c) the firing of U.S. Attorneys, particularly David Iglesias 
• Congressional Democrats refuse to accept "executive privilege" as an excuse to keep Rove from testifying under oath, and Bush didn't want to fight this bloody battle with Congress
• Congressional Democrats found a copy of the 5 million missing emails
• Colin Powell will soon reveal Rove's role in lying the nation into Iraq
• Polls show Republicans will lose in a landslide due to Bush's disastrous policies so the GOP's corporate backers threw him under the bus to help the GOP change its "image"

Bad reasons:

• He lost a crucial policy battle with Dick Cheney over Iran and U.S. bombing is imminent
• He has advance warning the economy is about to collapse and is getting out before the deluge
• He will be working for an evil Republican Presidential candidate
• Rupert Murdoch is hiring him at FOX News to help Murdoch take over the world
• Someone even more evil than Rove stole his job and blackmailed him into retiring

Why do you think Rove resigned?

Update 1: here are Rove's predictions for the 2008 elections:

Rove said he expects Democrats to give the 2008 presidential nomination to Sen. Hillary Rodham Clinton, whom he described as "a tough, tenacious, fatally flawed candidate." He also said Republicans have "a very good chance" to hold onto the White House in next year's elections.

Of course Rove predicted the GOP would win both houses of Congress in 2006, famously citing "The Math." Let's hope "The Math" is just as accurate in 2008.

Update 2: here are Rove's other predictions:

• Bush "will move back up in the polls" towards 40% - while the housing market is crashing?
• "Iraq will be in a better place" as the surge continues - with ethnic cleansing spreading, Maliki aligning with Iran, Parliament imploding, no electricity or water, more guns than people, and our occupation forces exhausted?
• In the fall, "the budget fight will have been fought to our advantage" - which means Bush will veto every Democratic bill. Will that finally convince Democrats to impeach him?
• "We'll see in the battle over FISA a fissure in the Democratic Party." Clearly Reid and Pelosi need to exert some party discipline to get conservative Democrats to oppose warrantless wiretapping by Alberto Gonzales.

Think Progress has Rove's record of failed predictions. PoliticsTV has Rove's video hall of shame.

Update 3: Sen. Pat Leahy isn't letting Rove walk away from his crimes:

Earlier this month, Karl Rove failed to comply with the Judiciary Committee’s subpoena to testify about the mass firings of United States Attorneys. Despite evidence that he played a central role in these firings, just as he did in the Libby case involving the outing of an undercover CIA agent and improper political briefings at over 20 government agencies, Mr. Rove acted as if he was above the law. That is wrong. Now that he is leaving the White House while under subpoena, I continue to ask what Mr. Rove and others at the White House are so desperate to hide. Mr. Rove’s apparent attempts to manipulate elections and push out prosecutors citing bogus claims of voter fraud shows corruption of federal law enforcement for partisan political purposes, and the Senate Judiciary Committee will continue its investigation into this serious issue.

The list of senior White House and Justice Department officials who have resigned during the course of these congressional investigations continues to grow, and today, Mr. Rove added his name to that list. There is a cloud over this White House, and a gathering storm. A similar cloud envelopes Mr. Rove, even as he leaves the White House.

Hey Pat - invoke inherent contempt and frog-march Rove before Congress!

Update 4: Joe Wilson reminds us that Rove should have been fired years ago:

Karl Rove’s resignation signals the final chapter in the Bush administration’s betrayal of the identity of a covert CIA officer. When this breach of national security occurred, the President promised the American people that anybody in his administration responsible for the leak would be removed. Rove, identified by the prosecutors as one of the leakers, not only was not summarily dismissed, but has been allowed to leave on his own terms, to praise from the President.

This sordid tale of compromising national security to cover-up and distract from the false rationale for the invasion of Iraq will forever remain in history a black mark on the Bush presidency.

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