Apple has managed to claim a respectable 22% share of the eBook market due to the success of its popular iPad tablet.
According to CEO Steve Jobs, the company has sold at over 5 million digital books to early adopters of the device.
Speaking at the 2010 WWDC in San Francisco, Jobs announced that an upcoming iBooks update would offer support for bookmarking, note taking, highlighting and PDFs.
"Publishers tell us that sales of there eBook sales are at 22% right now. 22% in iBooks," said Jobs.
"And we're making some changes today, [for example], notes, you can make notes right here, new bookmarks and a new page displaying your notes and bookmarks."
Meanwhile, MacWorld's Marco Tabini noted that iBooks support for PDFs would "extend" the app's ability to display books for a large number of new titles.
"[This is in addition] to all sorts of documents saved in Adobe's portable document format," wrote Tabini.
"[However], Jobs didn't mention whether PDF support extends to Adobe's proprietary DRM technology, which would make it possible to import and use books purchased through other bookstores that support the format."