Microsoft just pinged to remind that "As of January 11th, 2011 ConfigMgr SP1 Support has ended. The most current Service Pack organizations should be on to remain fully supported is Service Pack 2."
What does this mean? This link to Lifecycle Policy explains the detail of this for you. In April of 2010, there were some changes to these Policies. The Microsoft Support Lifecycle policy requires that the product's supported service pack be installed to continue to receive support (including security updates).
Here's a link to the new Service Pack Lifecycle Support Policy effective April 13, 2010.
[tags]confimgr 2007,sp1,confimgr 2007 r2,configmgr 2007 r3,configuration manager 2007 r3,configuration manager 2007 r2[/tags]