The salient point here is probably the 'gentleman's ain't'. The gonna, where the going to indicates future tense, is so common that even Joe Biden used it in the VP debate with Palin. And the use of to plow adds to the folksy air. I haven't heard the audio, but I'm guessing that Pawlenty didn't actually adopt a Southern accent.
The knock on Mr. Pawlenty, according to conversations with voters, is that his speeches sound sincere but do not always sizzle. At a faith forum last week in Iowa, he displayed vigor. But the next day at the Statehouse, the talk among several Republicans was that it seemed he had suddenly developed a Southern accent as he tried connecting to voters by speaking louder and with more energy.
The political blog of Radio Iowa heard it too and noted, “Pawlenty seems to be adopting a Southern accent as he talks about his record as governor.” As he spoke of the country’s challenges, he dropped the letter G, saying: “It ain’t gonna be easy. This is about plowin’ ahead and gettin’ the job done.”
Image from reason.com.