This is a WARNING. There are many reports of this new site (that claims to be a social network) spamming ones entire address book without permission or warning.
I received an invitation from Euan Semple to join him on this network and accepted (based on my complete trust of Euan) Later when I attended a meeting with him I learnt of the outrageous and unacceptable behaviour of this site. It seems that the spamming can occur at any time after initial sign-up and the act of resigning from the site often triggers spamming.
HAVE NOTHING TO DO WITH QUECHUP!! and tell all of your Friends.
It seems that Quechup is operated by the iDate corporation: Shame on you!