The rolling distributions aren't what most people call a real distribution. They are not meant to be stable. They are not meant to be used in a production enviroment. They are for testing purposes only.
Depending on where we are in our testing the rolling can be a beta, a release candidate, and for a short time, will even match a current release.

The development team of Scientific Linux does not garantee that 30rolling will work. We want to make that clear. Although the rolling releases might work just fine for the majority of the time, we might also just happen to be testing some product that does something you don't want it to do.

Here is where you can get Scientific Linux 30rolling
Main Distribution ftp://ftp.scientificlinux.org/linux/scientific/30rolling/SRPMS/
Source RPM's not modified ftp://ftp.scientificlinux.org/linux/scientific/30rolling/SRPMS/vendor/
CD Images ftp://ftp.scientificlinux.org/linux/scientific/30rolling/iso/