I guess this article is going to fail to mention anything about Straight Talk service that offers unlimited everything for $45/month and they now offer a bring your own smartphone device which works on either T Mobile or AT&T..I myself am using a iPhone 4 on AT&T and paying $48/month after taxes for unlimited.
you can do the same with Net10. There is a jailbreak for it. But also mention it's only certain phones and certain markets that allow for the T and TMO-USA phones.