Next OS update will be free, after that not so much.
Along with the Golden Master version of the iPhone OS v3.2 SDK, which made its way to developers yesterday (also the foundation platform to develop iPad apps for), Apple also included two other new files: an iPad firmware restore file and the end-user licensing agreement (EULA) for iPad.
While most of the EULA is the regular mundane stuff that you wouldn’t probably read (not that great of a developer you are then, eh?), there is one particular statement that mentions that future OS updates for iPad may not be free. In the statement, Apple explains that while it will provide free iPad OS updates from time to time, up to and including the next major iPad OS release following the version that the iPad will be shipped with. However, the next-to-next major OS update not be free. The example notes that, if iPad is shipped with v3.xx, Apple will provide free updates up to and including v4.xx, however, beyond that for say v5.xx, Apple reserves the right to charge users for the update.
This is similar to the iPod Touch, where users have to pay $9.95 for every major OS update.
Quote from the statement:
Apple will provide you any iPad OS software updates that it may release from time to time, up to and including the next major iPad OS software release following the version of iPad OS software that originally shipped from Apple on your iPad, for free. For example, if your iPad originally shipped with iPad 3.x software, Apple would provide you with any iPad OS software updates it might release up to and including the iPad 4.x software release. Such updates and releases may not necessarily include all of the new software features that Apple releases for newer iPad models.