The new pricing model is called the "Perpetual Model" and is detailed on the following PartnerSource pages:
To keep up to date on all information relating to the launch of Microsoft Dynamics GP 2013, visit the Launch Portal:
Please see the following posts from around the blogsphere:
Inside Microsoft Dynamics GP: New Pricing for Microsoft Dynamics GP 2013 Announced Today
Inside Microsoft Dynamics GP: Napkin Pricing
Microsoft Dynamics Partner Community Blog: Perpetual Licensing: NEW with Microsoft Dynamics NAV 2013 & Microsoft Dynamics GP 2013
Dynamics University: Big Changes Coming to Microsoft Dynamics GP Licensing
Dynamics Univesity: Dynamics GP Starter Pack and Extended Pack Modules
Make sure you read the detailed analysis and module lists in the Dynamics University blog posts by Eric Gjerdevig (links above).
Hope this information is helpful.