I'm not sure how anyone can refer to our current bond situation as a 'bond bubble'. Are you implying that the intrinsic value of the bonds are going to bust? If so, I would certainly think that if the value of the bond market crashes, the equity markets will be right there with it.
In most of the historical 'bubbles' we've experienced, it has been that we expect unreasonable or speculative returns. I'd guess that anyone who purchases a low single digit bond doesn't expect anything more than his money back at the end.
Rather than a bubble, I'm pretty sure this is simply a supply/demand situation coupled with a little central bank nudging. It's more than likely that many people are fed up with wall streets fooling around with the equity markets.