HD-DVD kind of lost its last battle to Blu-Ray in last month when Warner Brothers announced a shift from HD-DVD to Blu-Ray. Here is a nice graph that shows except for Universal Studios and Paramount Pictures every one sided with Blu-Ray.
Here is pie chart that depicts this share :
Barnes & Noble probably decided that all their Universal Studios HD-DVD inventory must go and hence is offering 50% off HD DVD sale. They have up to 95 HD-DVDs on sale.
If your total is $25 you can get free shipping.
Here are some other items that are going on for sale at Barnes & Noble.