Configuring pfSense software to work with Amazon Virtual Private Cloud (http://aws.amazon.com/vpc/) has always been a hassle.  There are HOWTO articles, such as http://www.heitorlessa.com/site-to-site-vpn-pfsense-and-amazon-vpc/, but people fail to achieve success even with these. 

Since we'd like to make it easier to do, we issued release 2.1.5 of pfSense software yesterday that contains a new feature if you're running on hardware purchased from Netgate or the pfSense store. 

There is a document that has some details on what it looks like here:

http://www.netgate.com/doc/AWS-VPN-appliance/AWS_VPC_Wizard_user_guide.html

We will be adding to that document over the next few days, but that gives you an idea how much simpler it is than the very long and tedious process that had to be performed when this was configured manually.  There is also support for BGP or static routing in the configuration wizard.  The wizard can configure either routing type and the process is pretty much identical other than having to enter a BGP AS number if you choose BGP routing. 

We plan on submitting an image of the new release to the marketplace ops team in the next few days so it will be available on instances of our AMI as well.  Finally, we will be re-issuing our VMware-certified pfSense appliance with support for the VPC wizard.