Frequently coders are called upon to figure out if designs are possible, and also help order new features in schedules, but when it comes to actively providing creative input, each company varies wildly. Some don't have many dedicated designers and the coders are meant to "add value" while developing the features. In other companies there is a very strict "if it's not in a design doc, it's not going in".
So, choose who you work for carefully.
Also, it's very possible for a coder to move to being a producer, which can lead to some more creative control, but I've not yet seen a good designer start out as a professional coder. (being a computer games enthusiast turned bedroom coder doesn't count, as many games designers have to start trying their ideas out somewhere)
This distinction of mine seems to have stirred up some feelings, so let me elaborate:
Games developers that are first and foremost coders, the ones that started out by coding, then realising that they liked computer games and then started to develop them became games developers, those games developers I would say are probably a bit hit or miss for being games designers.
The ones that started out by loving games then attacking SDKs with gusto, the ones that make mods, generate a lot of random stuff in game creation kits, only finally getting into a job where they code much later, those are games designers that can code. These ones, often, have the feel for games design that makes them good games designers.
Admittedly, I'm one of the former, I do love coding games, but for the joy of developing the game, and in the case of my home projects, for seeing the reaction from my family when they play the games I make for them. I am, however, aware of my shortcomings when it comes to games design. I have to try really hard not to be blinkered into thinking like a coder when designing games. I have to stop myself from adding features just because they're simple, and stop myself from trying to avoid adding features just because they're hard.
The coders that started out by designing annoy me with their tolerance for shabby code, but when I take a step back and see what they've done with the code, I have to be humble and admit that they made the game better, regardless of how annoying they might be to work with when it comes to code cleanliness.
I found a rare one at my last job that was the combination of both and wish him much luck in the future.
So, although coders can be involved in the design process, add their own creativity to the mix, I think it's probably better to sum it up differently:
Design meetings can include coders and designers, sometimes they even have the right job description.