Square Enix have been busy since E3 2009, with a ton of information filtering out about their games. The majority of it has come from Japan, but that doesn't mean that Square Enix don't care about their European audience.
Their line-up for GamesCom is pretty extensive, with the only notable exceptions being Final Fantasy Versus XIII and Kingdom Hearts Birth by Sleep; their exclusions are quite understandable though.
Both Final Fantasy XIII and Final Fantasy XIV will be represented at the convention, with the lead producers of both projects attending the event. This could mean that some new information is squeezed out of them, and that's probably going to be the most likely source as it's doubtful that Square Enix will have any huge announcements of their own as a company.
The Final Fantasy Crystal Chronicles: The Crystal Bearers is also going to be shown at the event, which all but completes a Final Fantasy line-up that appears very similar to that at E3. Nier and Front Mission Evolved will also be shown, as well as some Western titles, such as Order of War and Supreme Commander 2.
In short though, it's unlikely that there will be a bevy of big announcements, but some interesting information could be extracted from interviews.
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