There is a lot of useful information at the following site. Here is their explanation of the name. Sometimes this word is a brand name that should not be translated, and other times, it is a generic term.

About the term "Webpad"
National Semiconductor trademarked the name "WebPAD" in 1998, where "PAD" stood for Personal Access Device. That's why you'll sometimes see "WebPAD" instead of "Webpad" used by companies building Webpads based on National Semiconductor's CPU. The term "Webpad" quickly became highly descriptive of the device, which in effect rendered the trademark moot (the same thing happened to "Aspirin"). However, to avoid using the trademarked name during 1999 and 2000, many writers referring to Webpads other than National Semiconductor's reference design used either "web pad" or "web tablet", which further confused the terminology. In this article, I stick with "Webpad", which seems to be the most common usage on the Internet today.
http://www.pencomputing.com/frames/textblock_webpads.html