John At The Center

It could simply be that the two markets, nominal and real government securities, are segmented, telling us little about expected inflation. There has been a great deal of demand for nominal Treasuries (more on the short end but also on the longer end, and don’t get me started on 30-year Treasuries), so the spread could simply be due to the drop in nominal yields and an increase in real yields.

http://www.economist.com/blogs/freeexchange/2008/11/whats_the_matter_with_tips_the.cfm