EDIT 2014-02-07: Eclipse Luna is here, and support for Tomcat 8 is included in the bundled WTP : ) Happy days!
Tomcat 8 is still in development, but
UPDATE: Eclipse Mars EE and later have native support for Tomcat8. Use this only if you have an earlier version of eclipse.
The latest version of Eclipse still does not support Tomcat 8, but you can add the new version of WTP and Tomcat 8 support will be added natively. To do this:
Start Eclipse and you should have a Tomcat 8 option available when you go to deploy.
