Krugman's love for Germany's economic strategy

Paul Krugman - economist at Princeton University, and awarded the Nobel Prize of Economics in 2008 - almost always composes his posts in the New York Times Blog in a fairly sarcastic manner. But this time I really don't get what is his problem with the German economic strategy.

Germany's Economics Ministry stated:

Germany's surplus is "a sign of the competitiveness of the German economy and global demand for quality products from Germany."

Mr. Krugman complains that this is not at all a reason to celebrate. He says, that it only means that Germany is saving instead of investing, therefore not thinking in its future. Better to invest in countries, which need the money right now - Greece, Italy, Spain, etc.

Hmm... I'm not sure if I understood his critique correctly, nor would I dare to compete with a nobel prize awardee. But... does he really think that Germans store their savings under their pillow? I'd rather suppose that they deposit their money in their bank account. And what does this bank do - right, it does invest it. So, I don't get his point, why a trade surplus for an exporting nation like Germany should be a bad sign... Any comments?!