This was taken from an article in Financial Times published March 26, 2010.
"A sign of the strains across US fixed income markets was this week’s historic rupture between the 10-year Treasury yield and its close derivative, the interest rate swap.
For the first time since swaps emerged in the mid-1980s, the 10-year swap rate traded below that of the 'risk free' 10-year Treasury yield. Analysts say this reflects how government debt issuance has altered the dynamics between 'risk-free' yields and swaps, which reflect borrowing costs for non-sovereign borrowers."
Trading below the "risk free" 10-year Treasury yield means that the market sees the interest rate swap as less risky than a 10-year US Treasury Bond!