VPC and AZs when using ELB and Auto Scaling

Here are a couple of things to be aware of when using Auto Scaling, VPC, and ELB with Auto Scaling:

1. There is a limitation on ELB in regards to AZs and subnets.   You can only have one subnet per AZ.  You will most likely be creating an ELB (and using VPC) when using Auto Scaling so it is important to understand this.
2. When creating an autoscaling group (as-create-auto-scaling-group), make sure to specific the VPC subnets and AZs if you are using .  The VPC subnets need to be in the AZs specified in the AZ parameter for the as-create-auto-scaling-group command. No checking is done to make sure this is true so it is up to you to make sure these AZs actually exist in the subnets you specify. 

AWS VPC public and private subnets

What is the difference between a private and public subnet? I asked myself this after I was looking for a field in the ec2-describe-subnets command, AWS console, and ElasticWolf, and could not find anything to indicated whether a subnet was private or public...

Public and private subnets are more or less the same thing.  The routing table will decide whether a subnet is public or private. A subnet with a default route to the Internet Gateway, and instances using Elastic IPs, is considered as public. If you remove the Internet Gateway, you now have a private subnet.
This means that instances in a private subnet are invisible to the outside world and don't have access to the outside world (i.e internet).  Therefore, instances in private subnets need to make use of a NAT instance. The NAT instance will basically accept all traffic coming from the private instances and send it out to the Internet Gateway. That would theoretically add some latency.

Back to my original question: So, if an IGW is associated with your subnet it is a public subnet.