There are many avenues of exploitation, and as you're noticing, they constantly evolve. Your best bet is to attend a major conference like Black Hat, take copious notes from the briefings, and learn from the people who are actively exploiting systems today.
The speakers know that by the time they finish writing a book it's likely going to be out of date, and won't sell. That's probably why there aren't too many books on the topic. At least they take time to present what they've learned at these conferences, though, so there is information available.
If you have the chance (and the budget) the training sessions held at Black Hat are where you'll pick up the most specific and current knowledge on exploiting software. For example, the Exploit Laboratory is a two day course, followed by two more days of Exploit Black Belt training. Taking both would set you back as much as $6,000 (that's in addition to the $2K needed for Black Hat registration), but if you absolutely need these skills, it's an investment in yourself.
If you don't have that kind of money, DEFCON is only $180, a lot more casual, way more fun, and you'll have the chance to meet and hang out with the speakers. Quite a few of them are the same speakers giving the same presentations they gave at Black Hat; others are a bit more anonymous.