The Microsoft Language Portal is focused on bi-lingual glossaries/terminology, but Microsoft sites also contain various English-only glosssaries that explain key concepts and focus on smaller sets of terminology for the product/technology. These key terms are already included in the terminology search feature on the Language Portal.
Here's a non-exhaustive list of these general and specialized English-only glossaries:
Technologies et al
For more monolingual, specialized glossaries for particular products or technologies, search for "glossary" and/or "terminology" on the Microsoft homepage or the MSDN developer network site.
What happened to the Microsoft Language Portal?
If I click on the first link in this post, or try http://www.microsoft.com/language, I get an error saying "We are sorry, the page you requested cannot be found."
Is it temporarily offline or have you decided to scrap the service?
Looking into this one. Hopefully back soon....