Short-term it might be risky, in that without knowing exactly when the recovery will re-stimulate general aviation, you might have trouble getting an entry-level CFI job.

Long-term, now is probably a good time to start. Aviation has always been cyclical, and those who wait until until things are booming often become competitive just about the time the downswing starts again. If you do manage to get hired at the tail end, you will then be furlough fodder.

If you are ready to go with certificates in hand and 1500 hours in your logbook (plus 200+ ME), you can catch the beginning of the wave. That way your seniority will progress rapidly as folks are hired behind you, improving your QOL and reducing furlough risk.

Despite what SkyHigh says, there will be mandatory major airline retirements starting in Dec 2012, and that should drive some hiring although the exact amount depends on the state of the economy, fuel prices, war, swine flu, etc.

Just make sure you are fully educated and 100% committed to this career path before you lay down the money. If you do not have a private pilot license yet, DO NOT commit to a training program...get a PPL on your own first, do some recreational flying and see how you like it. Don't quit your day job until you have done that.