Rice that carries the cholera vaccine

It's not ready for human use yet, but researchers have genetically engineered a rice that carries the cholera vaccine. This is a big deal because many underdeveloped countries don't have the means to refrigerate regular vaccines, plus this method of delivery could have some advantages other vaccines don't -- such as triggering immune reactions in mucous membranes.

I generally don't like the idea of genetically modifying food for any reason, even though this one does seem worthwhile. I just worry that GM foods haven't been around long enough for us to really understand the long-term effects they might have.