The new rule is nicknamed the 3-1-1 rule. It applies ONLY to liquids and gels. There are no new rules concerning items that are not liquid or gel. So food, no problem.
3-1-1
3 as in 3 ounces or less. Each container of liquid/gel must be no larger than 3 ounces.
1 as in 1 quart-sized zip-top bag. You can put as many of the above containers in this bag as you want, as long as the bag is able to close comfortably.
1 as in one such bag per person.
So, if you ask if you can bring a bottle of water from home, now that you know the 3-1-1 rule it's obvious that the answer is NO, since that bottle will be larger than 3 ounces.
After you pass through security at the airport, you can buy anything you want at any of the shops on THAT side of security, and take it onto the plane with you. In other words, if you take a bottle of water from home, they won't let you through security with it. But after you pass through security, you could buy an identical bottle of water and then go on the plane with it.
All of the above has to do ONLY with carry-ons -- there are no new restrictions about what you can or can't pack in checked baggage.
www.tsa.gov has all the info you'll want, but please post back if you have any specific questions -- there are a lot of people here who'd be willing to help!