You could've Google'd or used the Search function here. And not post it in User Submitted News. The update came out a while ago.
Anyway, the update is to fix a problem for Wii Sports Resort. From what I heard it can brick some Wiis, but I don't know what's on it that makes it occur. I could be misinterpreting things, though.
If you're not planning on getting Wii Sports Resort, then there's no need to update.