The WSUS product, and thus the WSUS Remote Admin Console, as well as the WSUS SDK are all freely downloadable products from microsoft.com (however they do require licensed Windows operating systems for deployment).
I'm not aware of any limitations concerning customizations of the Remote Admin Console, but I suspect the preferred mode of distribution is going to be: [a] "Customer" installs their own registered WSUS server from microsoft.com [b] ISV/SI provides customized Remote Admin Console to "Customer" for use with installed WSUS Server.
I'm not aware of any provisions for redistribution of WSUS components; in fact, even 'redistributing' the WSUS installer is frowned upon, in deference to having the customer actually "register" at Microsoft's distribution site.
Whatever provisions/restrictions may or may not exist would likely be documented in the WSUS SDK, available for download from http://www.microsoft.com/wsus. Lawrence Garvin, M.S., MCITP(x2), MCTS(x5), MCP(x7), MCBMSP
Principal/CTO, Onsite Technology Solutions, Houston, Texas Microsoft MVP - Software Distribution (2005-2009)
Microsoft is conducting an online survey to understand your opinion of the Technet Web site. If you choose to participate, the online survey will be presented to you when you leave the Technet Web site.