So i am loving the new slime spawns and i tried to set a small test world in 1.4.2 pre. I started my game and went to a swamp biome, and setteled down. Nigth time came and ofc the slimes started to spawn, now the slimes spawned all over even some in shallow waters, how ever they cannot swin or so I have read on the wiki. So they just seemed stuck there. Further more since they allways move in a straight line they would get easily stuck in water small water holes (its a swamp doh).

Come the second night there where so many of the original slimes left that allmost no other mobs would spawn.

3. night one single Skelly archer rest was pure slimes do to the fact they dont seem to despawn and just get stuck, some eventually get so deep i think they drown but still they are slowly taking over swamp biomes with each passing night

This might need some tweaking, since i doubt its a intended feature.