I love me a good mug of cereal! Especially because you can drink the milk more easily after all of the cereal is eaten
I've done the mug before.
Actually my preferred way for oatmeal. Warms the mug up, and it stays warm for longer!
With the right cup I prefer it that way. To be honest I eat cereal dry 99% of the time anyway and a pint glass is perfect for pouring the sugary oats into my mouth hole.