UPDATE: The External Connector License is obsoleted. The connector was removed from the pricelist in January 2014. From the quick reference guide:
"Access by external (third party) users is included with the Server License; you do not need CALs unless using Microsoft Dynamics CRM client applications. External users are users that are not either your or your affiliates’ employees, or your or your affiliates’ onsite contractors or onsite agents."
One of our customers, working on CRM 2011 on-premises, would like to provide the access of CRM data to external parties, like their service providers, customers and other contacts. At present, these people have been created as contacts in CRM. I was asked to prepare high level design, a work model that allows this group of people to access the Dynamics CRM data. I have prepared a design wherein we decided to give access to external parties via the existing web site of my customer. I have also explained that we require External Connector License for this implementation. However, as I never used it before, I would like to collect more details on External Connector License.
I thought once we purchase such uncommon license from Microsoft, they would allow us to assign it to one of the existing Dynamics CRM users and the credentials of that user can be consumed at web portal then to fetch/update CRM data. To validate my understanding, I put the same as question on different Dynamics CRM communities, forums and groups.
I found that my conception was wrong. The External Connector License is just a paper license, a trust license. It has nothing to do with the implementation. To validate the cost for this license, you can refer below link.
http://crmpublish.blob.core.windows.net/docs/Pricing_Licensing_Guide.pdf
You could also refer the below links that help me to confirm it.
http://social.microsoft.com/Forums/en-US/crmdevelopment/thread/6843ac17-4946-4ac4-8e88-22a5fae3e425
Note: The External Connector License is not applicable to Dynamics CRM 2011 online
Please feel free to update this post with your experience about External Connector License.