Is it safe enough to make use of Google Sites?

All I can tell you is that Google is going to be around for a while, and you can be sure your information will be secure and safe in a Google Site. I would not trust Orkut quite as much, but definitely Google Sites is going to be around. More people are joining Sites every day, and Google makes plenty of money off of ads people put on their Google Sites using Adsense. No one can absolutely ure you that your information will be safe, but that would be the best place on the internet.