I think it is smart to take the test right after graduation, esp. if you get a good score - it's good for 5 years, who knows what you will be doing in 5 years. Does not hurt if you have $250 laying around.
However, i think taking the gmat after graduation only emphasizes that you had a long term plan and strategy. Even when you were still in college when all the other kids were only thinking about the immediate future. I think it looks better than the guy who took the test a few weeks before the deadline...
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