Possibilities are endless.... but
So you are correct that there are many, many possibilities to merge social media information into retail marketing or stock picks for that matter. However, before people move to using big data technology for processing social media information, we anticipate that most companies (keyword here is "most") will start with using technology like Hadoop to off load their existing "big data" technologies which have tended to be proprietary and expensive, and move some of that data and associated processing to Hadoop. So while Hadoop won't replace existing ETL and DW appliance technology, it does provide additional capabilities at a different price/performance point. I expect that companies will start using Hadoop with what they know already, getting the data they already have to be more cost effectively managed first, then move on to using these new technologies to tackle new problems like the one you mention.
