The New York Times takes a look at the hard drive market.
Strong demand for external hard drives was one of the highlights in consumer electronics last year. Americans spent $600 million on external hard drives in 2006, an increase of 53 percent over 2005, according to NPD, a market research firm. Put another way, consumers bought 739.7 million gigabytes of hard-drive storage space last year, more than 11 times as much as they did in 2003.
Merrill Lynch recently issued a report on the future of the HDD market including information on the potential threat of flash. You can get to the full report from here: http://vantelo.com/rss/2007/03/19/merrill-lynch-2007-the-year-ahead-hdd-buring-issues-january-2007-20-pages/
There are quite a few reports on storage. http://vantelo.com/rss/category/servers-storage/