Client chunk lighting updates fail.

I don't know if this is a bukkit thing or a minecraft thing, but whenever I create large areas of flat land for building on SMP (And my example is about 150x150 blocks). A lot of chunks won't update their lighting. I can add/remove lights, add/remove blocks, everything, but things won't change. What's even more weird is that parts of the chunks, the upper halves closer to the sun, will update but things below a certain point won't. I would like some help here, if this is a bukkit issue I understand that the creators are hard at work to update, so I won't bother them. If it's something else I would gladly like to know. Thanks.