Just some basic help wanted!

Hey,
I'm new to PLSM. What I want to do is generate a large map (including some floating areas).
I've managed to get PLSM to compile, but I'm really confused - what tool can I use to generate a map, and what format does the map splitter expect the map to be in?

Taking your questions out of order:

MapSplitter uses DevIl (or at least it used to, I haven't used it in a while), and can read just about any format you can imagine. MapSplitter wants either an 8-bit or 16-bit greyscale heightmap saved as a bitmap -- for example a PNG. If I recall correctly it also will take raw height data (ie no bitmap headers, just a series of heights).

You can create these in any graphics application. Terrain generators like Terragen can export in compatible formats.

I stumbled upon this wiki entry you might be interested in:

http://www.ogre3d.org/wiki/index.php/DCC_Tools#Terrain_generation