Hi. Good question. I found this info in a Forbes article:
The term “prosumer” has transformed from meaning “professional consumer” to meaning “product and brand advocate.” Rather than simply “consuming” products, people are becoming the voices of those products and significantly impacting the success or failure of companies, products, and brands, particularly through their involvement on the social web.
No longer are businesses completely in control of their products, brands and messages. Today, consumers are in control. The leaders of this shift are the members of the social web — bloggers, microbloggers, forum posters, social networking participants, and so on, who spread messages, influence people around the world, and drive demand.
Prosumers are the online influencers that business leaders and marketers must not just identify but also acknowledge, respect and develop relationships with in order for their products and brands to thrive.
Here is the url for that article:
The Shift from CONsumers to PROsumers - Forbes