How does devaluing a currency help a government deal with it's national debt?

Considering Greece’s current crisis, there is a lot of talk about how the country will cope with its debt. Of course, being a member of the EU, currency devaluation is not an option. Nevertheless, I’d very much like to understand why and how devaluing a currency helps a government deal with it’s debt situation. I [...] http://bit.ly/qDiTrY