MBA is certainly not a tool to get good placements, it should be considered as an investment for our own learning and knowledge enhancement purpose. Hence, it will be a bit unfair to judge the timing of doing a MBA taking the current market trends into consideration.
Although practically speaking, since MBA courses these days require such high investments, one is forced to think of the ROI.
Therefore more than recession or investment, 'doing an MBA' decision depends on how a person perceives the ROI, in form of learning or in form of good placements.
Anyhow, the recession is not permanent, the world market is bound to recover any time soon.
Cheers....... best of luck