Awesome article about the etymology of the word maverick and John McCain's use of it: http://www.nytimes.com/2008/10/05/weekinreview/05schwartz.html?no_interstitial

Or you can read it here:

October 5, 2008
The Nation

Who You Callin' a Maverick?
By JOHN SCHWARTZ

There's that word again: maverick. In Thursday's vice-presidential debate,
Gov. Sarah Palin of Alaska, the Republican candidate, used it to describe
herself and her running mate, Senator John McCain, no fewer than six times,
at one point calling him "the consummate maverick."

But to those who know the history of the word, applying it to Mr. McCain is
a bit of a stretch — and to one Texas family in particular it is even a bit
offensive.

"I'm just enraged that McCain calls himself a maverick," said Terrellita
Maverick, 82, a San Antonio native who proudly carries the name of a family
that has been known for its progressive politics since the 1600s, when an
early ancestor in Boston got into trouble with the law over his agitation
for the rights of indentured servants.

In the 1800s, Samuel Augustus Maverick went to Texas and became known for
not branding his cattle. He was more interested in keeping track of the land
he owned than the livestock on it, Ms. Maverick said; unbranded cattle,
then, were called "Maverick's." The name came to mean anyone who didn't bear
another's brand.

Sam Maverick's grandson, Fontaine Maury Maverick, was a two-term congressman
and a mayor of San Antonio who lost his mayoral re-election bid when
conservatives labeled him a Communist. He served in the Roosevelt
administration on the Smaller War Plants Corporation and is best known for
another coinage. He came up with the term "gobbledygook" in frustration at
the convoluted language of bureaucrats.

This Maverick's son, Maury Jr., was a firebrand civil libertarian and lawyer
who defended draft resisters, atheists and others scorned by society. He
served in the Texas Legislature during the McCarthy era and wrote fiery
columns for The San Antonio Express-News. His final column, published on
Feb. 2, 2003, just after he died at 82, was an attack on the coming war in
Iraq.

Terrellita Maverick, sister of Maury Jr., is a member emeritus of the board
of the San Antonio chapter of the American Civil Liberties Union of Texas.

Considering the family's long history of association with liberalism and
progressive ideals, it should come as no surprise that Ms. Maverick insists
that John McCain, who has voted so often with his party, "is in no way a
maverick, in uppercase or lowercase."

"It's just incredible — the nerve! — to suggest that he's not part of that
Republican herd. Every time we hear it, all my children and I and all my
family shrink a little and say, 'Oh, my God, he said it again.' "

"He's a Republican," she said. "He's branded."