"The heavy traders who would really benefit from zero-commission (assuming that it actually is) are on desktops in front of 4-10 monitors. Because of what it implies, I think regular people probably shouldn't be making trades that need to be done RIGHT NOW before a desktop can be reached."

Those people don't pay $10 per trade. If you do enough volume, you're usually able to negotiate much lower commissions. In addition, some of them will also specifically route their orders to ECNs and benefit from credit gained for providing liquidity to even further reduce their fees. All in all this is clearly designed for retail traders aka dumb money. I'd be willing to bet that their business model is based on selling the order flow they generate to institutions.