Germany has ensured that the IMF are involved in the bail-out plans for Greece (a) so that it will share the burden with non-European countries, and (b) so that its interest rate is lower than that required from the free market for purchase of Greek bonds, but it is also higher than the IMF-set rate which makes it almost-acceptable to its domestic voters and perhaps even not quite unconstitutional since some other party was offering assistance at a lower rate so their offer must therefore be anything but a free ride to the Greeks.
The hope is that this offer of 5% or so rates for Greek bonds will be enough to strong-arm the free market rate down into that vicinity and this will be bearable for the Greeks so the EU/IMF bail-out will not need to be called upon after all.
Me? I think there will be a brief period of calm as this is digested, in fact today I can see the Euro is up strongly against the Dollar. I don't see this lasting more than a few months at best before the fundamental insolvency of Greece (as many other places) comes back to the forefront though, but what would I know?