Well, with all the hype surrounding this new game in the Metroid series, and sheer difficulty of finding some of the information online, here's a nice guide to all the stuff we know about Metroid Other M so far, from the leaked intro footage, trailers and other released information:
The Introduction
There's a bit of a recap of Super Metroid in the intro, with the battle between Samus Aran and Mother Brain, including the young Metroid and the powerful beam attack... oh wait, there's a quick zoom across space and a planet exploding before this bit in the intro, but still. It's a really nice, nostalgic touch.
But never the less, after the usual bit (Samus gets nearly defeated, Baby Metroid sacrifices itself to help her beat said boss), she wakes up in what seems to be a hospital. She pretty much explains much of what we already knew, ending with her mention of Zebes being destroyed. And blowing the heck out of Mother Brain with the Hyper Beam. She then says how Mother Brain was destroyed (duh), the Space Pirates (obviously not all of them, unless Prime 3 and what not is to be mistrusted) and Ridley (that probably won't last long will it?). She then gets called over (simulation? Training?), and she puts on her Power Suit again. That's it.
You can see it here:
http://metroid-database.com/#266
And a quick photo recap here:

There's also a trailer, which can be seen below. This is officially released I think: