I think it is useful to differentiate between three kinds of reciprocity, the one that is really person to person, the one that is based on an exchange with a whole community, and a hybrid form in between. It seems to me that p2p-exchange platforms are useful for all three of them, and together they substantially strengthen a new type of trust in strangers, which was very difficult to instantiate before.

For example, a LETS system, if I understand it correctly, facilitates the exchanges of services person to person; when you work for linux or wikipedia as volunteer, you are exchanging with a whole community, “give a brick, get a house”. But projects like couchsurfing introduce in my opinion a third dimension, i.e. trusting a strange person, because he/she is part of the community platform that you trust, and though you will create a relationship with them once you visit, the reciprocity is not personal, and they may never come to your place, but instead, someone else from the community will.

Michel

I know, in this more transient world, that old tit-for-tat is a helpful start to a mutually-generous relationship – knowing that other person neither tilts to far as a “taker” or a “giver” means that she/he has adequate self-esteem and ability to sept into another’s shoes to help that person in the ways he/she will appreciate. This is vital to long-term peer2peer growth.AND it helps when online communities are designed to reinforce that “Mutuality” that matters so much for “us” to be uppermost on our minds – at least some of the time