Apple sells US$9.99 versions of its iWork app (Pages, Keynote and Numbers) for the iPad. However, it seems that the iPad’s crippled support for iWorks documents is causing frustration for some users.
The problems relate to the Keynote and Pages apps for the iPad and how these apps support certain features when documents are imported to the iPad from Keynote and Pages for Mac. You can read more here: http://blogs.zdnet.com/hardware/?p=7935&tag=nl.e539 .
However, Apple does have KnowledgeBase articles related to both Keynote and Pages for the iPad that outline the limitations. You can find ’em at http://support.apple.com/kb/HT4066 and http://support.apple.com/kb/HT4065 .