The blog The Elegant Variation recently had an extensive series of posts dedicated to the book, including a long excerpt here and an interview here. I haven't read it yet, though I'll definitely be looking for it the next time I am in a bookstore. Here are a couple of paragraphs, from immediately after G.H. Hardy receives his first letter from Ramanujan in Madras, with several pages of groundbreaking mathematical proofs attached:
Hardy shifts Hermione, much to her annoyance, off his lap, then gets up and moves to his windows. Beneath him, two gowned undergraduates stroll arm in arm toward the archway. Watching them, he thinks of asymptotes, values converging as they near a sum they will never reach: a half foot closer, then a quarter foot, then an eighth… One moment he can almost reach out and touch them, the next—whoosh—they're gone, sucked up by infinity. Now there's a divergent series for you. The envelope from India has left a curious smell on his fingers, of soot and what he thinks might be curry. The paper is cheap. In two places the ink has run.
This is not the first time that Hardy had received letters from strangers. For all its remoteness from the ordinary world, pure mathematics holds a mysterious attraction for cranks of all stripes. Some of the men who have written to Hardy are genuine lunatics, claiming to have in their hands formulae pointing to the location of the lost continent of Atlantis, or to have discovered cryptograms in the plays of Shakespeare indicating a Jewish conspiracy to defraud England. Most, though, are merely amateurs whom mathematics has fooled into believing that they have found solutions to the most famous unsolved problems. I have completed the long-sought proof to Goldbach's Conjecture—Goldbach's Conjecture, stating simply that any even number greater than two could be expressed as the sum of two primes. Needless to say I am loath to send my actual proof, lest it fall into the hands of one who might publish it as his own…Experience suggests that this Ramanujan falls into the latter category. Being poor—as if mathematics has ever made anyone rich! I have not given the actual investigations nor the expressions that I get—as if all the dons of Cambridge are waiting with baited breath to receive them!
Nine dense pages of mathematics accompany the letter. Sitting down again, Hardy looks them over. At first glance, the complex array of numbers, letters, and symbols suggests a passing familiarity with, if not a fluency in, the language of his discipline. Yet how strangely the Indian uses that language! What he is reading, Hardy thinks, is the equivalent of English spoken by a foreigner who has taught the tongue to himself. (link)
Personally I find this type of approach -- using the novel to work as an outlet for research on real historical problems -- very rewarding. Teaching Barker's Regeneration last spring, I found found that students got a lot out of the cross-referencing of actual historical documents (i.e., relating to Siegfried Sassoon and the development of modern psychology) with the literary text at hand.