ABC News’ Sheila Marikar (@SheilaYM) reports: While a cinematic love letter to Sarah Palin is set to debut in Iowa Tuesday night, a more critical film about the former Alaska governor is in the works. British filmmaker Nick Broomfield is shopping a documentary that examines Palin's life and rise to prominence through interviews with her parents, friends, colleagues such as ex-legislative director John Bitney, ex-Senate president Lyda Green, ex brother-in-law Mike Wooten and many more. In a preview clip from the film, Bitney and Green bemoan Palin’s habit of using her Blackberry during meetings. “It was frustrating at times to...