A quick and experimental survey of the solicited messages in the EmailKarma inbox shows that ~50% of messages received in the month of August are not authenticating (total neutral = 59) or are not passing (total fail = 12) one of the four main authentication technologies (SPF, Sender ID, Domain Keys or DKIM).
Inversely the last 8 days worth of spam received (1547 messages) shows that only 24 messages (1.5 %) have been authenticated in a positive manor. The largest set of spam messages are sent from domains that are not supporting authentication off any kind thus becoming an easy target for spoofing or forgery.
Based on these numbers our spam to email ratio is 91%.
If your looking to get noticed and your looking for help getting your campaigns to your users make sure your authenticating. ISPs and businesses are already beginning to evaluate the presence of these solutions and make delivery decisions based on their accuracy, and results.