OpenTv is slated for release in Spring. Initially available only in the (then) new 4900 and 3900 receivers, the OpenTV service is also available on the 301 and PVR501/508. Models 3800 and 4700 receivers have been upgraded to 3900 and 4900. The PVR721 is scheduled to get OpenTV in 2Q03. No extra hardware will be needed as this is a software service.

The first new interactive services powered by OpenTV will be a new style EPG with the TV picture optionally in the corner, and an instant weather channel, sort of like channel 201 iNews on the DishPlayer, except this channel will just be weather. There are over 1000 cities and national parks available.

For more information see: http://www.opentv.com/ and http://www.dishretailer.com/opentv.html
Games come from http://www.luditv.com/
Dish Network has expamples of the new services available through the Dish Home menu at http://www.dishnetwork.com/content/products/itv/index.shtml
 

Thanks to a contributor, Here's some more information on OpenTV and Dish Network's new 4900 receiver.