Ksplice is an open source extension of the Linux kernel

 Ksplice
 
Ksplice is an open source extension of the Linux kernel which
allows system administrators to apply security patches to a running
kernel without having to reboot the operating system (Dynamic Software
Updating).
Ksplice has been implemented for Linux on the x86-32 and x86-64
architectures. It was developed by Ksplice, Inc. until 21 July 2011, when
Oracle acquired Ksplice and started offering support for Oracle Linux.
Support for Red Hat Enterprise Linux was dropped and turned into a free
30-day trial for RHEL customers as an incentive to migrate to Oracle Linux
Premier Support Additionally, anyone can use Ksplice Uptrack for free on
Ubuntu Desktop and Fedora.
 
features:
 
   - Easy to set up
   - Ksplice Uptrack works perfectly in virtualized environments or on bare
   metal.
   - Rollback capability
   - No performance impact
   - Ksplice Uptrack supports using a standard HTTP proxy to pass through
   your firewall.
   - Conveniently check whether all of your systems are up to date, in one
   place, in your web browser.
   - Secure infrastructure
   - email announcement whenever new updates are available for one of your
   systems.
   - API and monitoring
   - Set access policies for individual or groups of machines.
 
Home page: http://www.ksplice.com/
for Binary package and other details:http://pkgs.org/search/?keyword=ksplice

Thanks to dhanasekar @ kaniyam.