You can generate a 1.9 map (with the 1.9 pre2 client) and flying around (using creative mode) and check it out.
IF you use a custom seed (like, tonesisgay) AND the seed generation code doesn't change between 1.9 pre2 and 1.9 release, AND the seed you generate is pretty frickin slick, let me know.
Chombo and I have been screwing around testing this stuff, and are trying to find a seed that generates a cool map (preferably with a large flat area around 0,0, large oceans but large land masses, and actual snow would be nice too...
Anyway, this is all just if you want to screw around, as there is no guarantee a seed generating a cool map in 1.9 pre2 will be the same map in 1.9 release, or that we'll use that seed.