On a quality stationary cutting tool, such as a table saw, radial arm saw or bandsaw, the table platform is very often made of cast iron, which is a durable surface that is very stable and vibration free, but which can also be susceptible to rust. Usually, the units are shipped with a special protective grease that's been applied to prevent rust during shipping and warehouse storage. This coating needs to be cleaned off thoroughly before using the saw, and it is probably a good idea to then apply a protectant to the table before indulging in that first cut.
There are a number of quality lubricant/protectants available on the market specifically designed for saw tables. Any merchant who specializes in fine woodworking tools should have a few different varieties from which to choose. If you don't have any on hand on the day that you set up your new pride-and-joy, simply dig through the shelves in your garage and find an old can of car wax.
Carnauba-based paste wax is designed to protect your car's finish from the elements, and it will perform the same task on your saw table. Simply rub it on liberally with a damp sponge and let it dry for a few hours. Then buff it out with a clean cloth. Put on a second coat if you feel that it is necessary, but be sure to remove all of the wax out of the miter gauges.
You'll want to put on another coat every month or so, just to keep the table in tip-top shape. This will keep your table surface clean and slick, allowing workpieces to glide through the saw smoothly.
Lower quality tools may have tables made from steel or even aluminum, and while protecting these surfaces is not going to prevent rust, there is still merit to keeping the table surfaces clean and slick. The monthly waxing routine is a good idea for any stationary tool with a metal table surface.
One thing to keep in mind: you should never use silicone-based products on your saw tables, as this can leave a residue behind that can interfere with the finishes on some types of wood.