This is a huge thing - Germany couldn't run its huge trade surplus without its currency appreciating and reducing its competitiveness otherwise. It's a pretty bad deal for the consumption-based Eurozone economies though - they have to internally devalue instead of just being able to devalue their exchange rate.

It's one of the major problems with the Euro... It was a terrible idea from the start, and situations like Greece were foreseen by economists like the great Wynne Godley decades ago (see Maastricht and All That, London Review of Books, Oct 1992). Unfortunately the mainstream of economics still doesn't have a developed enough understanding of monetary systems to have worked that out yet...