During today’s WWDC keynote address, Apple CEO Steve Jobs revealed several enhancements to the iBooks app for the iPad. The new version will offer highlighting and note taking, with an option to bookmark a page and have the bookmark appear in the table of contents. In addition, the new version of iBooks will offer support for reading PDF files. Jobs noted that the iBookstore has seen five million downloads in the first 65 days, for an average of 2.5 books per iPad, and offers books from five out of the six largest publishers in the U.S., taking a 22% share of eBook sales in just eight weeks. The updated version of iBooks will be released later this month.