For concise news on the changed social security tax rates for 2011, see New Changes in Payroll Taxes, a post by Autum Awalt at the Faith-Based Accounting blog.
If you outsource payroll, the post gives you the info to double-check the calculations.
If you prepare payroll in-house, the details can help you make sure your software updated correctly.
The article also points out the deadline for applying the changes and then another deadline for making any needed corrections.
Check out the article for details and then double-check your calculations.