Over on the MacRumors iPad forum, someone asked why the authors of jailbreak tweaks don't release their apps to the general unjailbroken public. This question indicates a fundamental misunderstanding about what jailbreaking actually means, one that I think is quite common.
So what does it actually mean to jailbreak your iPad?
When your iPad arrives brand-new from the store, there is only one way to get apps onto it: Apple's App Store. Whether directly onto the iPad or via iTunes, the App Store is the one and only place where you can download apps and install them onto the iPad.
Apple has 100% control over what appears in the App Store. There are good reasons for this - for example, because Apple tests every app before approving it, malware doesn't make it into the App Store Andy thus has no way to make it onto your iPad. But there are certain types of apps that Apple simply doesn't allow, such as those that make system-wide changes or affect iOS itself. And there are other apps that can't be approved for other reasons - for example, VLC is a popular media player on desktop computers. But VLC, and thus the VLC app, is written using code that is covered by the GPL (Gnu Public License), and some of the App Store's terms conflict with the GPL. Thus, distributing the app in the App Store would violate the license its code was written under.
So where does jailbreaking come into this? Well, jailbreaking your iPad does exactly one thing: When you jailbreak your iPad, it adjusts the code so that it is possible to install apps from a source other than Apple's App Store. That's all. Well, and it installs Cydia, which is just an alternate app store. So once you've jailbroken, you can download apps from Cydia that Apple would never approve, like ones to change the appearance of your icons or reassign what happens when you click the home button.
Of course, the downside is that since Cydia doesn't have the lengthy approval process of the App Store, there is the possibility of malware or just bugs in tweaks that are system-wide. But it's not too hard to Google a package before you download it to make sure it's legit - and the one time I had one that messed things up a bit, it all went back to normal once I deleted it.
I think that a lot of people hear the "break" part of jailbreak and think that it somehow involves breaking the iPad or iOS itself - it doesn't. The one and only thing that changes when you jailbreak is where you can download apps from - until, of course, you start downloading them and tweaking the things you want to tweak.