It's funny. When my pediatrician told me that my great eater would one day get picky, I didn't believe her - not because I thought I had the perfect child, but because I could not imagine someone going from loving everything to liking nothing literally over night. But, alas, it happened. I've had the problem with two children (one is now 3 and one just 17 months) and found that there were two different roots to the problem.
The first child just simply got picky and started turning his nose up at everything. The second one also got picky and wouldn't eat a morsel at dinner until I discovered that his issue has nothing to do with the food. He won't tolerate anyone else holding his spoon. He has to do it. Period. If he's in control of the spoon, he shovels anything and everything in. Given that he's 17 months he is probably on his way to being picky, but right now it's a spoon thing and that was a real surprise for me.
Our policy is to not make a huge issue out of the fact that they won't eat, BUT we do not make them separate meals. I cook one meal for the family, taking into account everyone's tastes but not being held captive by them. The boys are welcome to eat or not eat. If they don't eat, they are not rewarded with play time. We simply begin their bedtime routine (which usually starts after dinner anyway). I found that by 17 months old they do absolutely fine sleeping through the night without having eaten dinner.
My older son is able to understand rewards, so he will get a "surprise" (usually a few M&Ms) if he eats nicely for a few days in a row. He often considers this reward and then tells me, "No thank you mom. I think I'd rather go straight to bed." Bottom line - you can't make them eat if they don't want to eat. I have found that the more of an issue we make out of it, the more they dig their heels in. So, I don't make the table a battle field and I don't make them sit there until they have eaten. They do, however, have to sit there until the rest of the family has finished eating.
One note - If I'm in the mood for a meal that I really wouldn't expect most children to like I will make a separate dinner, but I feed them early and then sit down to a nice dinner with my husband once the kids are in bed. I don't like to highlight the fact that they got a separate meal by all sharing the same table. This is more the exception than the norm, though.
R.