Why her views are unclear:

The fact is that Palin's most consistent religious home has been the Pentecostal church of her youth. Though her family left the Wasilla Assembly of God in 2002, just before she launched her campaign for lieutenant governor, Palin has continued to return. The now famous prayer to protect her from witchcraft took place during a visit in 2005, three years after Palin's official departure. She returned again as recently as June 2008, making reference to that earlier service and crediting the African pastor's prayer with leading her to gubernatorial victory. And when she works from the state capital, Palin attends the Juneau Christian Center, an Assemblies of God congregation.

The article next explains the Pentacostal faith. It's also gaining among Christians. As for well-known pentacostals:

Who are some famous Pentecostals? Some of the most prominent televangelists have been Pentecostal, including Jim and Tammy Faye Bakker, Jimmy Swaggart, Pat Robertson and T.D. Jakes. John Ashcroft, the former U.S. Attorney General and Senator from Missouri, is a member of the Assemblies of God and is the first Pentecostal to have attained such high political office.

....Nearly 20% of American Pentecostals are Latino, and they make up a rapidly growing constituency in the U.S. that supported George W. Bush in 2004 but is shifting over in greater numbers behind Barack Obama this year. In addition, a handful of African-American Pentecostals hold high positions within the Democratic Party, including Joshua Dubois, Obama's religious outreach director, and Leah Daughtry, chief of staff at the Democratic National Committee.

Background here and here.