Register the twitter certificate with sharepoint 2010

$root = New-Object System.Security.Cryptography.X509Certificates.X509Certificate2("C:\Maintenance_Sarah\VeriSignForTwitter.cer")
New-SPTrustedRootAuthority -Name "VeriSignForTwitter.cer" -Certificate $root

SharePoint 2010 and Cert Trust – Could not establish trust relationship for the SSL/TLS secure channel

http://www.brainlitter.com/2012/03/13/sharepoint-2010-and-cert-trust-could-not-establish-trust-relationship-for-the-ssltls-secure-channel/

Integrating Twitter into SharePoint

http://spmatt.wordpress.com/2013/02/01/integrating-twitter-into-sharepoint/