This is from a few days ago, but it is the most complete compendium of refutations of the various Social Security Zombie Lies that I've seen.
No, life expectancy at age 65 has not changed all that much, and those changes were anticipated.
No, the beneficiary/taxpayer ratio is not an important issue.
No, you can't do better investing the money in private sector funds (and people wouldn't do it anyway. 25-year-olds do not save 15% of their gross for retirement).
I'm hoping that Digby's panel on this topic is on the list of ustreamed content from NetRoots Nation.