In a message to the opensuse-project mailing list, openSUSE developer Greg Kroah-Hartman announced a new project - openSUSE Tumbleweed. openSUSE Tumbleweed will provide a rolling release for those openSUSE users who wishes to have a rolling release. It will essentially be a repo containing the latest stable versions of the applications.
This is how Greg described openSUSE Tumbleweed:
I'd like to propose "openSUSE Tumbleweed" a repo that is a rolling updated version of openSUSE containing the latest "stable" versions of packages for people to use.
Greg also explained the the difference between openSUSE's Factory and Tumbleweed. While Factory always have bleeding edge versions of the packages, which may result in the packages not working properly together, Tumbleweed will only have the latest stable versions of the packages after they have been verified to work properly.
As for the packages which will make it to Tumbleweed, it will be left to the maintainer of the packages to decide if their package is stable enough to push it to the Tumbleweed repo. The Tumbleweed project will be started after the release of openSUSE 11.4.
This does not mean that openSUSE is moving to a rolling release. The normal release schedule will stay. Tumbleweed is just another choice for those who prefer a rolling release.