The Supreme Court's decision earlier this month to uphold the McCain-Feingold Campaign Finance law was one of the few bright spots for progressive politics this year, and as such drew a very hostile reaction from the Right. The gist of the decision was that it halted in its tracks the opinion that the expenditure of money was in and of itself protected "speech" under the First Amendment. The majority opinion was attacked by one pundit as being comparable to Plessy v. Ferguson in its violation of the "clear meaning" of the Constitution, an odious comparison when you realize that the Plessy decision legalized apartheid in much of the country, and ensured that the most-despised and least-powerful segments of our society stayed that way, whereas the Court's decision three weeks ago infringes on the "rights" of the most affluent and powerful groups in America.
That the expenditure of money is even thought to be protected under the First Amendment in the first place shows how ideas that would have been considered extreme thirty years ago now have acquired a mainstream legitimacy, thanks to the conservative dominance of the media. Casual readers of the Bill of Rights might find some difficulty with the notion that campaign contributions are part of what is considered "free speech". The First Amendment does not mention the spending of money, or even the words "money" or "spend"; it mainly deals with restrictions on the power of Congress to infringe on speech, religion, and the press. Laws against bribery were on the books at the time the Constitution was drafted, and do not appear to have been questioned or challenged by the Framers.
Back when I was in law school (1985-8), the high court's 1976 decision in Buckley v. Valeo was considered to be a turning point in the history of the judicial branch, away from the liberalism of the Warren Court and towards a jurisprudence that was friendlier to the wealthy and powerful. In that case, the court struck down provisions of the post-Watergate campaign reform act that restricted expenditures by political candidates themselves, while upholding contribution limits by third parties. In the intervening years, those same third parties were able to create entities that were, at least on paper, independent of actual campaigns, but could spend unlimited amounts to ensure the election of a candidate. The McCain-Feingold Act was drafted to specifically address this loophole, while people like George Will and Senator Mitch McConnell believe the Court didn't go far enough in Buckley.
The difference between campaign "contributions" and bribery is a subtle one. If I were to announce that I had given George Bush's reelection campaign a million dollars in exchange for his veto of any bankruptcy law that I happen to oppose, I would be prosecuted (at least in California; I doubt John Ashcroft would bother). Yet there is no question that my offer to the President has specific free speech implications, in much the same way that the manufacture of child pornography has; if we use the standard of George Will, I'm using wealth to openly propound an opinion on an issue of public policy, an activity clearly protected by the First Amendment.
In reality, though, what the Right views as "free speech" is really a claim to an entitlement, a property right, to control government. It is a cornerstone of conservative thought that government should not interfere with the individual's (or corporation's) right to do what it pleases with its property. Modern liberalism, on the other hand, believes that there is a governmental responsibility to draw some boundaries as to what people can do with their property. Restrictions (or even outright bans) on campaign spending should be no more considered a violation of free speech than the employment of children in factories at sub-minimum wages.