Depends... Globally? None. This has happened before (even in similarly developed countries - see Argentina) and will happen again. For Europe? It's now clear

Depends... Globally? None. This has happened before (even in similarly developed countries - see Argentina) and will happen again. For Europe? It's now clear that countries in the euro zone can default. A few years ago this was associated with the risk that private lenders will turn away from other Southern European (Portugal, Italy, Spain) countries, in turn raising their interest rates and thereby also pushing them into bankruptcy. Now that most debt of Greece is owned by either the ECB, EFSF or the IMF and the bond markets seemed to be back to business as usual this isn't a huge risk anymore. Long term it might mean that lenders will do some due diligence even for countries of the euro zone (then again, many of them got to sell the Greek bonds at full value to the ECB, so who knows...) Edit: As you wrote "forgiven" - debt is usually not forgiven but renegotiated once the indebted country stops (or threatens to stop) servicing said debt in the hope that an agreement can be found which is better then a unilateral default.