Oblivion has not been delayed.
The official release date for the past 5 months has been "Holidays 2005", and it still is. Retailers and Magazines make guesses (such as the day one launch for Xbox360). Just because they have made guesses about the release date, it doesn't mean they were correct to begin with.
Gamestop said Oblivion for PC would be released in early may, before there was an official release date. Have Oblivion been delayed since then? Of course not.
Proper place for release date info:
http://www.elderscro...blivion_faq.htm