the rundown on cleaning:
* warm soapy water
* boil (Toys in Babeland says 10 minutes, MyPleasure.com says 2-3)
* top rack of the dishwasher
...and then air dry
Blowfish suggests rubbing (isopropyl) alcohol for the ultra-paranoid. Then again, the comparable situation would be sex toys used in a monogamous relationship, and hopefully you're not sharing your cup. In our situation, soap and water is fine.
Don't use silicone-based lube! (And don't use lube containing glycerin, glycerol, sorbitol or anything that ends in -ose, which is the chemical suffix for a sugar.)
Also, once a rip or hole has been made, the material is easily ripped further. So be nice to your cup (don't give it to your dog). Similarly, sex toys will warp and crack if stored in awkward positions that stress the toy. Storing your cup in such a way that it is squashed is probably an unwise idea.
Toys in Babeland