Is it possible to upgrade Jenkins from Jenkins it-self?
Yes, it is possible. In Windows, this is what I see when there is a new version available:


When you click the Upgrade Automatically button, Jenkins downloads and install the new war file itself.

Please, check Jenkins wiki for further details. There are some problems if you installed Jenkins from a Debian package.


  If you run Jenkins with java -jar jenkins.war, Jenkins will be able to update itself from the Manage Jenkins page. This is the simplest way to do automatic upgrades.


*nix/Mac


  If you've installed via the OS X installer, the jenkins running the process does not own the .war file. To get auto-upgrade working, just fix the permissions so the jenkins user can write the WAR (in /Applications/Jenkins).


Debian Package


  Using the Upgrade-Button from within Jenkins (available since 1.318) will not work if Jenkins was installed from a Debian package (results in permission denied errors when trying to download the new WAR file)!


Windows Auto-Upgrade


  If you install Jenkins as a Windows service, Jenkins will be able to update itself from the Manage Jenkins page.