A recent acticle in Science (subscription required) estimates the number of patented humand genes at around 4,382, of the total of 23,688 human genes identified so far. According to the Personal Genome blog,

"While most patented genes have only one IP claim on them, some genes have many claims. The two most highly patented genes were found to be BMP7, an osteogenic factor, and CDKN2A, a tumor suppressor gene. The sequences of these two genes were claimed in more than 20 patents each."

Although the ethics and propriety of gene patenting is still up for debate, the biopharmaceutical companies stillclaim ownership as fast as discoveries are made. The Genetics and Public Health Blog, in fact, noted that Incyte Pharmaceuticals/Incyte Genomics already owns almost half the gene patents.