According to the fine print on the Skype iPhone app, free Skype to Skype calls will last all the way until the end of 2010. Yesterday, the date was given as the end of August, but it looks like we've all gotten an extension on Skype-to-Skype calling over 3G.
Now the prospect of payment has at least been delayed, possibly because of the outcry from users -- comments on the changes haven't been pretty. The Skype folks haven't explained the change, or the reason for the charges to begin with. We'll stay tuned, and keep our ears open for why Skype might have delayed the planned charges.