It's a non-issue in so far as it does not prevent bitcoin from working as it should if you do implement things as the original client does it, it's only an issue because it's something you might easily get wrong when implementing a new client (which apparently happened to some other developers), and it would have been avoidable - but changing the behaviour now has to be done very carefully, coordinating with all implementors of bitcoin clients, in order to make sure the fix does not cause a blockchain split, so that is what is happening.
This is not correct. The original client gets one edge case wrong and it is this that is causing the issue with most of the exchanges that use it: http://www.reddit.com/r/Bitcoin/comments/1xm49o/due_to_activ...
It is not "lose money" exploitable (unless combined with social engineering) but is definitely "lose time, lose effort" exploitable.