One of the reasons Zappos did so well was because they took commodity (shoes) + software (online store) + CS (where CS = customer service, not compsci) = purchase.
Most tech markets now are trading commodity products; even content is a commodity.
But you can still overcome the commoditization issues by finding something else to sell that's hyperspecialized - and some of the most interesting e-commerce marketplaces of the last decade scale precisely *because they commoditize long-tail items and create a barter platform that lets those locked out of the speciality markets participate in the trading.
Empowering individual sellers in a commodity market, aka 'normals' seems like it was a relatively efficient mechanism for growth in the last boom. Examples = information/ads (Google), long tail book purchasing (Amazon), and distributed social interactions (Facebook).
The more interesting question: are we seeing a return of selling to geeks, aka hyperspecialization?