Going beyond 2010, smartphones are projected to makeup 26 percent and 32 percent of phone sales in 2011 and 2012 respectively. Driving this will be the lower prices smartphones will command. Even this year, you could get a Palm Pixi for under $50 at some locations. I'd be willing to bet we'll see at least one smartphone given away free with a contract in 2010.
People are also increasingly interested in the features that allow them to access Facebook, Twitter, Google Maps as well as other location based service or social networks. There are some feature phones that can do one or more of these, but most smartphones can do all of these as well as the basics like email, music, video and more. The application stores are also being advertised on TV which highlights the versatility of the devices. If I had to guess, I'd say Gartner forecast is going to be under where the smartphone's share in two to three years will actually be.