Reader Z.M. asks: Two products I have seen, the Cisco/Linksys WIP330, and the Y5 World handset use Windows CE/Mobile for the OS and browser, but they do not have the full UI suite you see on Windows Mobile mobile phones. They both use what looks like the same 3rd-party UI kit for a telephony UI. I was wondering if you know who makes this software?
Microsoft provides the base platform for Windows CE that is used in embedded devices such as the ones you mention (and many more). This base platform is then molded and enhanced by independent developers to create products like the ones you mention. This is a large number of embedded systems developers working to develop these kinds of products.
Windows CE is also the underlying platform for Windows Mobile devices: Pocket PC, Pocket PC Phone Edition, and Smartphone. The Windows Mobile Shell, Office, and other teams add on the features you see on Pocket PCs and Smartphones based on Windows Mobile.