I'm not sure what the problem is. If I want to search for downloads, I first go to Microsoft Downloads. If you search from the main page, you can refine your results to only Microsoft Downloads from the search results page.
The search results are ordered by popularity, so if Powershell 2.0 doesn't come up on top, then it's because Powershell 1.0 is more popular. It takes all of .5 seconds to type "2.0" after "Powershell" in the search box. Or .75 seconds to change the sort order from "Newest to oldest" if you don't feel like taking your right hand off the mouse.
By looking at the way Powershell 2.0 is packaged, it's pretty obvious that it's no longer considered a standalone product. You either have to download it as part of the Powershell 2.0 SDK, or as part of the Windows Management Framework.
You can also see that you can't download it separately for Windows 7. It's only available for Vista, Windows Server 2008,
and Windows Server 2008 R2. As somebody already mentioned, it's already part of Windows 7. Perhaps this is why it's not considered a popular download, whereas Powershell 1.0 is.
Edit: Powershell 2.0 is included with Windows Server R2 as well.