If you use Google Reader, by going through the top navigation displayed across the Google Products -- you probably have notice that the Google Sites dsiplaced the Google's feed reader in the Google navigation bar.
To visit Google Reader using the Google nav bar, now you need to click "More" drop-down, and then click "Reader" from the drop-down list of Google services.
A Google employee explained that this is a permanent change:
"While the link to Reader has moved, you can continue to access Google Reader under the "More" dropdown. Or, you can also set a specific bookmark to reader.google.com for one-click access. Depending your browser, try dragging http://reader.google.com right from this post onto the bookmark bar on your browser (usually below the URL bar)."
So, why has it been done? Actually, Google services on the navigation bar are displayed on the basis of their popularity. The 'much popular' services gets place on the front-end, and less-popular movs to drop-down menu under "More". In this case, it's likely that Reader's popularity is declining, while Google Sites gains more users. According to Google Trends, the queries [google reader] and [google sites] have almost the same search volume in the US.
New Google Nav bar
Old Google Nav bar