Crank and chain rings wiggle

I doubt that you are seeing your crank or bottom bracket getting loose, although it is possible. And it would be smart to check that each of your chainring fixing bolts is indeed tight. I think more likely you are seeing a slight warp in your chainrings. That could be caused by a manufacturing defect (or just poor quality control), an accident or small impact, or it is possible that the chainring bolts are tight but have been tightened highly unevenly, with differing torques (which can be corrected by loosening all of them and re-tightening in increments with a good torque wrench).

What brand of crank and chainrings do you have?

Is there any odd noise coming from your crank when you put a considerable amount of force on the pedals?  My work bike, less than 1 year old Trek, started making noise and I hadd some wiggle the bottom bracket had loosened took the trek store 5 minutes to fix...  Otherwise try to tighten everything or like the last poster said could be warped...  How many miles do you have on them?