Just when it looked like Blu-ray was winning the next-generation DVD format war, an often overlooked yet powerful force -- porn -- has emerged to potentially swing the tide back toward rivalHDDVD.

Blu-ray has unquestionably been winning the battle of perception. Walk into a Best Buy store and the first thing you're likely to see is a wall of Blu-ray movies. HD DVDs, meanwhile, might be hidden around the corner and are greatly outnumbered by Blu-ray titles.

Then there's the endorsements. Blockbuster Video, the world's biggest rental chain, in June dealt HD DVD a body blow by saying it was expanding its high-definition offerings to 1,700 stores -- but they would be Blu-Ray only. The chain said it was bowing to customer preference -- 70% of next-generation format rentals in test stores were Blu-Ray, while only 30% were HDDVD.

Meanwhile, Target Corp., the second-largest department store chain in the United States, last week said it would feature Bluray players and discs starting this holiday season.

Both move