i have a friend at HKS who's on the adcomm, and last i spoke with her (about 2 weeks ago), we discussed exactly these things. i'll pass on her words now. many of you, i'm sure, already know this, but for those who have questions this will hopefully shed some light on the matter:
[*:3ayxtcjp]there is no minimum, no cutoff, but both V and Q scores are important. with that said, a higher Q score of 700+ is more critical; remember that GRE scores have percentages, and more people do well on the Q than on the V. for example, a V score of 700 might put you in the 96th percentile, while a 700 on the Q might put you in the 70th percentile.
[*:3ayxtcjp]there is a holistic approach taken to judging a candidate's eligibility, so a candidate who's been out of undergrad for a while and has more work experience will need to worry less about GRE scores than someone who completed his/her bachelor's degree in the past few years.
[*:3ayxtcjp]on a slightly unrelated note, this year the HKS adcomm has looked for applicants who clearly indicated their sincere desire to get into the public/government/nonprofit sector. in the past few years, a disproportionate amount of MPP grads (i want to say between 30 and 40%) have ended up in the private sector. while this is understandable, considering how expensive grad school can be, the administration has taken on aid/debt as a primary concern. i think jmoney referred to this earlier, maybe in this thread or another one.
i hope this helps!