To my knowledge, any fabric you can find labeled as "bamboo" is technically rayon produced from bamboo, just as "modal" is rayon produced from wood fiber (by whichever factory has the trademark on the name 'modal'). So for use, care, and shrinkage, treat it as such.

I have a few "bamboo" T's from a no-name manufacturer and can attest that they're very comfortable. If you're a horrible pear-shaped nerd you may want an undershirt to avoid sharing your nipples with the admiring throngs. (I am a horrible pear-shaped nerd.)