RapidSSL is owned by GeoTrust, which is owned by Verisign.
You can read all about GeoTrust's certificate practices here: http://www.geotrust.com/resources/cps/pdfs/GeoTrustCPS-Versi...
The results of their KPMG audit here: https://cert.webtrust.org/SealFile?seal=650&file=pdf
And their entry into Mozilla here: https://bugzilla.mozilla.org/show_bug.cgi?id=409236