New versions of Hudson are released often, and announcements are made on the old Hudson CI website at http://hudson-ci.org, as well as the new Hudson home on the eclipse website at http://www.eclipse.org/hudson.
An easier way of determining that a new release of Hudson is available is by looking on the Manage Hudson page for an alert in yellow at the top of the main panel, that looks similar to the following screenshot:
There may be two options for upgrading our Hudson installation
Download a new WAR file
Upgrading Hudson and the Team Concept feature
In some circumstances, the Upgrade Automatically option will not be available.
While upgrading Hudson to a new release, it is possible that there may be issues with plugin compatibility or something may go wrong during the upgrade process. For this reason, it is suggested that a full backup of the Hudson configuration is done before you perform an upgrade.