Berkshire's market cap is just under $500 bil, according to Yahoo, and the Apple position was worth approx $57 bil per that recent article. That would make the Apple position roughly 10% of Berkshire's value, so a pretty hefty position in one stock.
I only follow Berkshire loosely, and was surprised to hear about the big Apple position. I figured Buffett was being influenced by the younger analysts he has on his team.
Berkshire also took a sizable position in Teva, which I thought may have been touted by one of the younger guys also. Neither the Apple or Teva moves have panned out yet, but Buffett buys for the long haul so we'll see what the future brings. His decision to exit that GE position certainly was well timed. As I recall, he got those GE shares from a convertible security he obtained from GE during the 2008/09 debacle. GE had liquidity problems and Buffett came to the rescue.
News 
Market Data 
Discover 
