In the recent hype over iPhone App programming, I got my hands on a MacBook. I have an idea for a program. Can I just write it in Objective-C and distribute it, or must I register with Apple Developer Connection?
Does the OS X development / distribution process require Apple censorship like the iPhone does?
no, you don't need to pay anything to distribute your Mac OS application. Depending upon how you choose to distribute it, you can create an installer, or build an .app bundle that user puts in their application directory. You can host your distribution (such as your website) for people to download and install your software.
You can be sure that if the Mac was invented today, they would go with an AppStore. Fortunately, it is too late for them to change that.
So, no, you can just create your apps and make them available for download anywhere, just like with any other computer.
A difference compared to PC is that they do not care too much about backwards-compatibility, so you can expect to have to rewrite your apps every few years. But that is probably a good thing, as it keeps innovation going.
Registration with the Apple Developer Connection is completely optional, but you want to at least join their free offerings, as they have some good resources.
All you have to do is write it and release it. Same as you would for Windows, and any other computer.
A Tip: whatever you may think of the iPhone, it might be a good idea to try and get into the spirit of Mac development. Macs are pretty cool machines. The developer community is quite friendly. The way your question is worded suggests that you are starting out with a negative opinion.
As Seth, Thilo, and Darren say, you can distribute Mac OSX app's freely without Apple intervening just like PC app's are distributed.
However, you do have to join the Apple Developer Connection if you write up an iPhone/iPod Touch app. You'll need an actual paid membership for this, which goes for $99/year if I recall correctly. Also you're iPhone/iPod Touch app will be subject to Apple's rules to make it to the AppStore.