My understanding is that it isn't a HARP loan, but rather a HARP program that allows people to refinance even if they owe more than their home is worth. The program also allows you to take advantage of current low interest rates.
There's nothing special about the loan that would show up differently on a credit report. You need good credit to qualify for the HARP program. http://www.makinghomeaffordable.gov/...ages/harp.aspx
I've been the victim of "helpful" co-workers and relatives before - telling my exH that we would be subject to capital gains taxes when selling our house grrr