mitchellh/vagrant-aws — pull request #280 by ankushnarula (2014-08-14 03:35:40+00:00)
Title: m1.small has been deprecated in us-east-1 

m1.small has been deprecated in us-east-1 for newly created instances. Although the t-class instance types are less expensive, they only support hvm AMIs. The m3.medium instance type is the smallest instance type to support both paravirtualization and hvm AMIs.