ger87410 is right. Heat from our aquariums will not be suffienct to kill Ich. Most biologists use high pressure steam to kill off their buggies and sanatize their equipment. Most bugs, except those that live in thermal geysers and the such, are taken care of this way. So, while the bugs can't live at 212 F, obviously neither can your fish!
Now, the reason it is usually recommended to raise the temperature a little in your tank is that it speeds up the life cycle of Ich. Ich medicines can only kill them off when they are in their free swimming period of life -- NOT when they are on the cysts appearing as white spots on your fish. So, higher temperatures mean Ich grows faster, and the cysts burst sooner and then the medicine kills them faster.
Since the medicine only works on one stage in their life-cycle it is usually recommended to dose the medicine for several days (7-14) even after the white spots disappear to ensure it does not reappear.