The HARP 2.0 guidelines: (The major ones anyways.)
* Require that you purchased your home prior to June 1st of 2009
* No mortgage lates within the last 6 months and a max of 1 in the last 12 months.
* Only applies to Fannie Mae or Freddie Mac mortgages.
If your goal is to buy a new house and rent out your existing home you can still get financing but you need to be aware of some things.
If you can afford and qualify for both payments you will have a much smoother and easier time getting financing.
If you cannot afford both payments and need the rental income on your previous home, the lender per FHA and conforming guidelines will require that you have at least 20% to 30% equity depending on who you use for new financing. VA also has different requirements for this if you qualify VA.
Per what you mentioned above I don't think this will be the case since you are looking at doing a HARP loan.
You should talk with some local loan officers and see what your options are. I may have missed something or he/she may have a better idea or a good plan for you.
Just make sure you ask a lot of questions and I wish you luck.