Following is a bit tricky code what i discovered, may be its already known to few of us ..

Following is the url to access Public Knowlede Base of any Salesforce Org, just change the org id.
http://na1.salesforce.com/sol/public/solutionbrowser.jsp?search=donkey&cid=000000000000000&orgId=00D30000000XXXX

Only Assumptions above is that
* Org to have Knowledge Base to be Enabled
* A Solution named donkey to be defined already in Org

Does Public Knowledge Base means its public to everyone in this world who uses Salesforce Org. Isnt it should be public to only users or persons relevant to that Org. Addition of any unique identifier apart form Org id to increase Validation of Invoker.

My understanding of this may be completely wrong, just correct me if am wrong.Just saw something suspicious and felt to update salesforce developers, so came up with this post !!

Blogged @ http://community.salesforce.com/sforce/board/message?board.id=discuss&message.id=8291#M8291