The Court decided in favor of Citizens United in a 5-4 decision.
This is awful, awful news. From what I've heard, there will still be donation limitations, but corporations will be able to spend unlimited cash on things like TV ads, publications and so forth. Unions will be able to do the same.
UPDATE: TMP reports:
At the heart of the ruling, now available here (pdf), is a judgment by the Court that the law cannot distinguish between corporations and individuals in prohibiting speech - so free speech rights that apply to the latter must also apply to the former.