Are there any finish solutions for making "microwave-safe" wood items for serving food on?
It's not so much a question of "microwave-safe" finishes as "microwave-safe" materials.
Microwaves work by exciting water molecules, thereby increasing their energy (i.e., heating them up). The reason your wooden bowl gets hot is because of the water trapped in the wood fibers.
I would strongly advise against microwaving a finished wood bowl for not only the risk of burning one's self on it, but also because the rapid heating of the water in the bowl can cause it to crack.
I want to give a turned bowl to someone as a gift, but I know they will inevitably use these bowls in the microwave.
Very clearly tell the intended recipient that wooden bowls are not microwave safe. If someone uses the bowl improperly and it breaks, yes, that sucks for them, but you're not at fault having told them. Common sense has to factor into things sometimes.
By the way, not only would I tell them to not microwave the bowl, but don't soak it in water, and don't put it through the dishwasher either.