Not if you're talking on a global scale like Sidoh and others want me to. Else if we talked on a more local scale, then Microsoft's comment would be fine.
Now since we're talking on a global scale, until most of the users on the internet use it then it won't be mainstream and it's pretty obvious most users on the internet are using Windows..
And it's been said here at least a dozen times: just because most Internet web users aren't using it, doesn't mean it's not mainstream. Most sites use it, and the most popular sites use it. That makes it mainstream. Being in the browser will just mean that it's used more. That's it. What don't you understand about that?
Mainstream is, generally, the
common current of thought. It is a term most often applied in the arts (i.e., music, literature, and performance). This includes: * something that is not out of the ordinary or unusual;* something that is familiar to the masses;* something that belongs to an identifiable genre, such as detective fiction, horror, fantasy, or science fiction.
en.wikipedia.org/wiki/Mainstream
Common meaning majority, and again you are forgetting what microsoft is talking about when they mean mainstream. If they meant most popular websites, then yes you'd be correct. They will bring RSS to the majority of users and by definition it would become mainstream.