The Blu-ray V HD DVD was an interesting contest for us in the audio-visual industry. With different movie studios backing different formats it was very messy. i.e if you sided with HD DVD you would never be able to buy a James Bond movie as they are made by Sony who support Blu-Ray.
The battle was over merely by Toshiba announcing that they were stopping production of their HD DVD players. It was most likely Sonys clever placement of Blu-ray players in PS3 and making them relatively cheap that clinched it. HD DVD finalised their format before launch unlike Blu-ray which was rushed to market before the final standard was agreed.
Both formats are very similar but Blu-ray does have more capacity.
However, the industry feeling is "who cares". Consumer purchasing of disk media is short lived as downloading, streaming and media servers will become the norm. No-one is likely to replace their DVD collection with Blu-ray disks and at around £25 each, the public will buy Blu-ray disks less often than DVD.
More scary is the BBC and ITV plugging the "digital switchover" constantly and urging people to get digital TVs or set top boxes. Within a year, HD content will be broadcast on Freeview and immediately render ALL CURRENT DIGITAL RECEIVERS OBSOLETE. Obviously they want to take your money now and take it again next year.