To keep ahead of the game, I read one of the books for my "The Life of the Buddha" course starting in October. It was Karen Armstrong's Buddha. The book is written from a religious scholar's perspective, as Armstrong pieces together a loose biography of the Buddha's life. I didn't know what to expect from Armstrong, a comparative religion scholar and former Catholic nun; but I was pleasantly surprised by her treatment of the subject.
Her tone and style is (professionally) distant and academic, but not overly so. I found the writing accessible and engaging. The book is filled with interesting facts about the Buddha's time, including Vedic culture, plausible explanations for why the Buddha rejected the caste system, and even why Buddhists sit retreats. The book is short--187 pages total--and well worth the time. I saw a copy of her Mohammed biography at my local bookstore and, based on Buddha, I will definitely pick it up.
If you get a chance, give Buddha a read.