Adobe PDF reader quickly lost interest in PDF metadata and attributes like Author or Subject (what you see in detailed view mode in windows explorer). People who used this information to browse and organize their scanned PDF documents in windows XP immediately felt the problem. In later windows you can only see such properties using the PDF property page, which isn't very convenient for large collections of documents and neither you can search for such PDF information.
You can bring back this information in your windows explorer and other shell-aware file managers like xplorer² by installing PDF XChange viewer. Unlike Adobe, these guys know all about offering quality shell extensions that work both in 32 and 64 bit windows. When you install PDF XChange viewer you can tick off all components except for Shell extensions — if you are after a lightweight solution. This part of the program is completely free for all uses (including commercial).
As you can see in the picture to the right, after installing this tool the PDF columns come back to life and you can browse the missing details. Note that the Keyword property still isn't available in windows explorer but you can see it in xplorer². Moreover with xplorer² you can search and filter using such PDF properties as a rule.