There are Federal WARN regulations and there are state WARN regulations, look your state up to see what the rules are.
California WARN is better for the employee that the Federal.
SCA = Santa Clara
La Jolla (San Diego) apparently got WARN, which usually happens because 50 or more people have been let go from a specific job site (there's only one site in La Jolla), but I cannot confirm that 50 or more were let go there.
The WARN package is superior to the non-WARN in the following ways:
1) While your total severance is the same either way, with WARN you will get 4 regular paychecks and then a lump sum containing the rest. You get over-taxed on a lump sum, and while you will get it back you have to wait until you file your taxes next year to do so.
2) Effectively you are still employed for 60 days under WARN. This gives you time to refinance your mortgage or whatever other financial dealings you want to effect that are easier done when you have a job versus when you don't.
3) You have uninterrupted health insurance for 60 days. Other insurance continues as well (life, etc) until the end of the 60 days.
4) If you are in the 401k, contributions are still made and matched.
San Diego had less that 50 people let go back in January and they did not get WARN, so they got screwed compared to the most recent layoffs.