With the Summer '08 release we gave 2 free connections to all Unlimited, Enterprise and Professional edition customers. We saw a tremendous uptick in the number of connections and volume of data shared between connected companies. Based on your response, we've gone one step further with the Winter '09 release. With Winter '09, ALL customers (including Group Edition) may send invitations, accept invitations and share data FREE of charge. No limitations and no hidden costs!

Below are additional links on the service...

1) Website

2) Blog

So starting today all you need to do is activate Salesforce to Salesforce using the setup link (Setup|Customize|Salesforce to Salesforce|Settings) and start sending out invitations and connecting with companies you do business with.

If you have any questions please contact your AE, CSM or send your questions to product management at: s2s@salesforce.com