By Ben Steverman

Watching Warren

Berkshire Hathaway (BRKA) Chairman and Chief Executive Warren Buffett turns 80 this year, but he shows no signs of slowing down.

In just the past year, his endorsed candidate became the U.S. President, Buffett made the biggest acquisition bid of his career, and he profited from the financial crisis through deals that helped save marquee U.S. companies.

But even as the octogenarian-in-waiting has kept busy, shares of his operating company Berkshire Hathaway lagged the broader market badly in 2009, rising only 2.7% compared with a rally of 23% in the S&P 500-stock index.

As the world's most famous investor enters 2010, Bloomberg BusinessWeek is taking stock of Buffett's many holdings and activities. Click ahead for an overview of what is keeping Buffett busy these days.