I and some other colleagues received this notification via email to all our System Administrators:

"You have one or more certificates in your Salesforce org California College Guidance Initiative [org ID here] that will expire soon. Please review the list below and visit Certificate and Key Management from Setup to make an update.
 
   - SelfSignedCert_20Nov2013_203932, Self-Signed, expires on 11/20/2015. Warning: This certificate will expire in 30 day(s)"

Does anyone have any tips as to how I can check if letting this expire impacts us or not? Has anyone else seen this?