Rising bond yields are particularly troubling because 1) they are an accurate harbinger of investor sentiment that something is seriously wrong, and they are demanding higher compensation for the risk, and 2) it increases the costs of borrowing at precisely the worst possible time, just as the Eurozone appears poised to dip into recession. It's not just Italy and Greece, now, either.
Interest costs are rising steadily for Spain, Portugal, and now, even France, which has been assiduous in trying to protect its credit rating, even resorting to intimidation of the credit rating agencies. If France loses its AAA credit rating, it will no longer be eligible to backstop the EU's bailout fund, and Germany would be the sole surviving AAA-rated government big enough to try to bail out the weaker members of Europe, and Germany simply isn't strong enough or big enough to go it alone.
Worse yet, the bailout fund itself is have grave difficulties trying to sell its bonds, and investors simply aren't taking the bait and buying the bonds. The bond vigilantes are fleeing Europe in droves. Trouble this way comes.