The Supreme Court did indeed hand down its decision in Citizens United this morning. And as expected, it held that federal law's current restrictions on the independent campaign expenditures of corporations violates the First Amendment. In other words, the Constitution does not permit the government to treat corporations (or unions or any other sort of association, one supposes) any different than individuals. This means that corporations (and other associations) can spend as much as they want to influence elections. The split was 5-4, with the usual ideological division. (By a separate 8-1 vote, the Court upheld the law's disclosure requirements.)
There are two more shoes that seem reasonably likely to drop. As the law stands today, there are now greater restrictions on political parties than there are on corporations or labor unions. That makes no sense. The restrictions on party expenditures seem likely the next to drop.
Further, the Court's rationale seems to suggest that there is not much of a difference between independent expenditures and direct contributions. That is, if there is no concern about corruption (or the appearance of corruption) with the former, even though they have roughly the same impact on election outcomes, it seems that there could not be a constitutionally sufficient concern with the latter, either, to justify legal restrictions. Thus, the whole tower of campaign finance regulation seems likely to fall soon, at least so long as the Court's composition (with respect to the five in the majority) remains the same.
The full text of the opinion, which includes a 90-page dissent (!) by Justice Stevens, can be found here. A blog post with links to lots of coverage can be found here. And this blog, written by a terrific election law expert at Loyola LA, is worth checking out.