We started having a similar problem with our son around the time that he was 14 months old. Not sure if it was connected or not -- but he got REALLY sick for a few weeks and after that he has been INCREDIBLY picky.
We have tackled the problem by basically giving him what he wants and just trying to keep it healthy. Here are a few tricks we use --
1) We buy individual sized fruit cups (peaches, man. oranges, pears) and drain off the liquid before giving it to him. Flavored applesauce cups have also been great.
2) Gerber Yogurt Melts (a little expensive) but a really healthy snack.
3) Cheerios and another high fiber cereal as dry snacks
4) Whole Wheat Bread (with butter or PB/ PB & J)
5) Tyson Chicken Nuggets (your son may not be ready yet) but when he is Tyson nuggets are not greasy and are all white meat
The bad news is that the picky behavior did not quickly go away and we are still dealing with it. However, we keep offering things and some days he'll eat veggies and other things and then there are the days he won't.
Also, keep eating new foods in front of your son. This is what seems to spark our son's interest in trying things.
And finally -- don't let people bully you into forcing your child to eat. I am a BIG believer in giving the kids time to come around. Substitue with vitamins if you need.
Good Luck!