It seems that now everyone is starting to weigh on the “bond bubble”. The Economist had a panel of experts weigh in on the topic. As always I recommend people take the term expert with a grain of salt.
My take on the subject is we are not in a bond bubble per say but long term treasury bonds are an awful investment now. I am not commenting on any other bonds corporate, municipal, short or long term. I have not really looked into any of these bonds lately. However, it seems the yields are getting pretty low on all types of bonds. If you are holding short term bonds that are high grade (treasuries, good corporates) you should be safe. But all others bonds could involve significant loss of principal both in nominal and real terms. Click here for the link to the discussion on The Economist.
I also recommend checking out this article I authored in late 2009 when bond yields were much higher Is There Any Way To Get A Decent Yield Nowadays?