Well, the Berkshire Hathaway (NYSE:BRK-A) (NYSE:BRK-B) weekend is over, and all of the Warren Buffett faithful are making their way home. Closing out my "live" coverage, I'd like to wrap up my observations with a few more timely topics that were covered later in the day during the annual meeting's Q&A session.

On derivatives
Whitney Tilson, a well known Buffettologist and founder of Tilson Mutual Funds, asked Buffett and Charlie Munger for their thoughts on derivatives.

Derivatives are financial instruments that derive their value from some underlying asset. Futures on commodity prices and stock-market indices are two types of derivatives. They were originally created to help guarantee earnings in certain industries. For example, a corn farmer might buy futures on corn prices to lock in a certain price for his upcoming crop. While this is still done today, there are now derivative contracts for just about anything imaginable, and they're also widely used to speculate on certain markets. In recent years, the industry has absolutely exploded, and the excitement over the future of the industry is well demonstrated in the current battle involving InterContinental Exchange (NYSE:ICE) and Chicago Mercantile Exchange (NYSE:CME) for ownership of CBOT Holdings (NYSE:BOT).

Buffett's answer to Tilson, in a nutshell, is that something bad is going to come of the growth of derivatives, but it's hard to know when and how that will happen. He noted that an extreme amount of leverage contributed to the market crash preceding the Great Depression. The market needed a correction, all of the borrowed money that people were using on the market was like throwing gas on a fire, Buffett said. Since then, regulations have been put in place that put limits on leverage, but Buffett believes that derivatives make a joke of such regulations.

Munger chimed in by noting the number of people who are seeing record profits thanks in part to derivatives. As we know, with record profits come record executive bonuses -- and just as the monkey will do whatever it takes to get the banana, Munger said those executives will also continue to do exactly what they're doing to get their bonuses, tenable or not.

On alternative energy
With oil prices staying sticky in the $60s and the clean-energy movement continuing to gain momentum, it's not surprising at all that the topic of alternative energy came up a few times during the Q&A session.

On global warming itself, Buffett said he is not 100% sold on the notion, but he's also seen enough that he won't dismiss the claims. His view is particularly important for Berkshire when it comes to its insurance activities, since one of the potential effects of global warming is an increase in the number and severity of major storms. Buffett said he has worked a margin of safety into his thinking when it comes to global warming and its effects.

Munger, never one to mince words, said he might find it more comfortable if the world got a little warmer as opposed to a bit cooler. With regard to alternative-energy sources in particular, Munger shared his view that running cars on fuel derived from corn "is about the dumbest idea I've ever seen," in part because of the disturbing side effect it has on raising the price of food. Maybe it wasn't a friendly comment for Archer Daniels Midland (NYSE:ADM) shareholders, but it also wasn't all that surprising for those familiar with Buffett and Munger's views.

On Darfur, Planned Parenthood, and a dam on the Klamath
One of the very notable things about this year's shareholder meeting was the number of social and political topics that found their way to the floor. One shareholder was outraged that part of the fortune Buffett is pledging to charity will be going to Planned Parenthood -- though that's not surprising at all if you know Buffett's history. And an activist shareholder got an initiative on the proxy to try to force Berkshire to sell its holdings in PetroChina (NYSE:PTR) because of its alleged connections to the genocide in Sudan. Meanwhile, a third group was protesting a dam on the Klamath River in California that is owned by Berkshire subsidiary PacifiCorp.

Don't worry; I'm not going to get into politics here. It's hardly the place. What should be noted, though -- and Buffett and Munger seemed to understand this -- is that the more people and media attention that Berkshire and its annual meeting attract, the more opportunity certain groups will see to put forth their cause. For those who thought it was out of place at the meeting, all I can say is that you shouldn't be surprised to see more of the same next year.

Go back to Matt's original report to read all of his reports from this year's Berkshire meeting.

Berkshire Hathaway is a Motley Fool Inside Value newsletter recommendation. Looking for the market's best bargains on great stocks? Inside Value has you covered. And you can check it all out free for 30 days.

Fool contributor Matt Koppenheffer does not own shares of any of the companies mentioned. You can visit Matt on the Fool's CAPS service, or check out his CAPS blog. The Fool's disclosure policy always enjoys a good Omaha steak -- preferably at Gorat's.