There has been a FAQ of LittleBigPlanet 2 posted over at the PlayStation Blog highlighting some of the updates and features that will be available in the sequel, including backwards compatibility available from the first title.
A few big notes taken away from the questions were that all DLC and content from the first LittleBigPlanet will transfer into LittleBigPlanet 2 with no problems, meaning custom costumes and stickers will all be fully accessible without having to re-make anything. Another feature was that there will be custom narration available, meaning players can record their own narration for shared levels.
There are a few more questions over at the blog for those interested in learning more about what's what, and more details are expected to be released next month at E3, including more create tools to be shown. Stay tuned this June to see what happens over at E3.
Source: PlayStation Blog