Self-Deportation and the Dream Act
Self deportation may indeed work, and may already be working due to the current poor state of the U.S. economy.
However, with recent news of the U.S. military jobs being cut (see Reuters article below), how will this affect the number of available service member jobs for our own citizens if we plan to give them to those who are here illegally as a means for them to gain U.S. citizenship?
The overall size of the Army, which was already scheduled to fall to 520,000 by 2016, could be further reduced to 490,000, a drop of another 30,000 soldiers, analysts say.
http://www.reuters.com/article/2012/01/25/us-usa-budget-weapons-idUSTRE80O07R20120125
Publius Prime 
Good point. Hopefully there will be some sort of comptition mechanism for military recruit candidates to ensure the highest quality military force. Think there will be more people applying for military positions since the slow civilian job market doesn’t have much to offer.