As I mentioned above, multiresolution data refers to data that is stored using level-of-detail or LOD technology. You can think of this data as being stored in a ‘pyramid’ – with the top of the pyramid representing one single low/coarse resolution chunk of data, and the bottom of the pyramid representing many high/fine resolution chunks of data. When you view the data from far away, you will only see a low resolution chunk. As you get closer and closer, higher resolution data is paged into your screen.
The term streaming simply refers to the fact that the data can be streamed from any location – not only your local hard drive. The data can sit on a remote server in the multiresolution / LOD format, and your client software will request data to be streamed in as needed. Depending on your connection speed, streaming over a network can be nearly as fast as paging from your local hard drive.
Interesting company. And they're using OPeNDAP, WFS, WMS and SOS.