Social media is quickly altering the way consumers make purchase decisions, according to a new study by shopping comparison site PriceGrabber. While the research focused on retailers, the lessons are equally critical for players across the interactive media space. eMarketer has the full report. Highlights:

Generation Y (those born after 1979) online buyers are more immersed in online and mobile activities than any other generation: Some 85 percent of Gen Y respondents said they participated in social networking, and 57 percent reported involvement with blogs.

As a result, retailers have no choice but to jump aboard the social media bandwagon. The PriceGrabber survey, which was sponsored by Internet Retailer, found that 39.3 percent of retail respondents use social networks. Of these, 32 percent have a page on Facebook, 27 percent on MySpace and 26 percent on YouTube.

Avoiding social media means staying out of the conversation, not a wise move these days. A 2008 study conducted by the Society for New Communications Research for Nuance Communications found that nearly three-quarters of respondents choose retailers and products based on others’ customer experiences shared online. Discussion forums and blogs are the top sources for consumers to swap stories.

Are you posting to blogs? Have a FaceBook or MySpace page? Soliciting comments on reporting and service? Run, don’t walk…the Web is waiting.