There are so many new products, or I should say services for internet marketing these days. I guess the original ideas of these services, most of them are online, are designed for "friend-to-friend" communication; similar to SMS, IM, and mobile text messages.
It is amazing how business people, such as the "maker" of the online service, or a marketing / business guy turns these online services into marketing tools. Now that almost everything can be "shared"...