Meditation can absolutely help in fighting depression! It seems that often a contributing factor to our depression in the west (I know that is a generalization, but it is often true) is our persistent and circular thinking. Some, especially ancient cultures, have a way of slowing the mind so as not to get so caught up in the mind (the use of which is after-all, only one way of 'knowing').
Most of us use our minds at work (and not our bodies), we never let our minds rest (since we feel that 'haste makes waste'), we 'relax' by watching TV (which actually drains us of mental energy instead of building us up after a day of constant thinking), we move our bodies much less than our ancestors, we find it uncomfortable to just 'be' with someone without 'doing' something, and then - to top it all off - we try to THINK our way out of our sadness through so-called 'rationalization'.
It takes work - in the form of mental-training - to help our minds stop thinking 'way too much.' This is where meditation comes in. Many people find that a daily yoga, meditation, tai chi, or qi gong practice often helps them to 'quiet the mind.'
Someone once explained it to me like this when I first began learning to meditate. They said, 'Thoughts will come into your mind, this is inevitable. But you can choose not to dwell on them. It's kind of like when a plane goes overhead; you know that it's there because you hear it, but it doesn't necessarily cause you to stop whatever you're doing and you don't have to look up at it. The same is true of your thoughts. When a thought comes up and you may get a little lost in it, just remember to focus on your breath and not on the thought.' - Easier said than done, I know.
But helping train your mind to be less 'chatty' as I call it, can help calm your soul as well. It's helped me with my depression (specifically my circular-thinking), but it takes time to find a practice that works well for you. And once you find one, only then does the journey actually begin.
I think properly guided or practiced meditation can aid, along with sleep, exercise, diet, rituals, herbal supplements, professional help, and if necessary, possibly prescription drugs (though I would personally only advocate their use in a 'stepping-stone' fashion, in conjunction with other action, on limited term basis. ie: don't use anti-depressants alone, in a permanent fashion).
Meditation can be used to focus your mind, quiet the 'chatter', and observe your own thought process, if done properly. Done incorrectly, it could cause you to amplify the depressive cognitive self-talk, overly focus on it, and lead to more entrenched depression. Depression, by it's nature, lends to a clouded view of the world and oneself, and I would posit meditation asks one to set one's entire ego-self aside, which is one of the biggest difficulties of depression--one's own thoughts and emotions are negatively locked into themselves when depressed.
My experience has been when you first start meditating, working on developing full and focused awareness (such as on a candle flame, breathing technique, visualization of a process) while the stream of thoughts (chatter) goes on is what you do. Over time you will build a capacity and repository of awareness, so to speak, so that you may relax from focusing on something so specific, and can instead simply maintain awareness and actively observe the stream of thoughts from a place in consciousness outside of your immediate ego. At this juncture, that the opportunity to identify negative self-talk and constraining thought-patterns may occur, which has the possibility for you to yield major or minor breakthroughs in self-awareness and altering your cognitive patterns to be a happier person. Working with an expert in the field of meditation, or preferably a mental health specialist who has such credentials or background would be ideal.