From the Taipei Times (link):
The public is almost evenly split over whether the US would come to Taiwan’s defense if China attacked, an opinion poll suggested yesterday.
The poll conducted by the Taiwan Thinktank on the meeting last week between US President George W. Bush and Chinese President Hu Jintao indicated that 52 percent of the public expected US support should a war break out in the Taiwan Strait.
Political scientist Lo Chih-cheng of Soochow University yesterday said the result showed that the majority of people regard the US as a friendly ally.
However, Lo added that this view was at odds with public opinion in the US, as past surveys there on public support for the US sending troops to defend Taiwan averaged at only 30 percent.