iWork is Apple's suite of productivity software, including Pages, a word processor; Numbers, a spreadsheet program, and Keynote, presentation software (and what powers all of Apple's own presentations).
The iWork team has been hard at work on this stuff for more than a year, making it all multi-touch and iPad ready. Keynote, in particular, is really impressive: It looks like it's easy to view and add slides, make edits and add options. Everything is optimized for touch.
Pages is also optimized to be used without a standard keyboard and mouse (we really hope it will at least be an option), with formatting options quickly accessible and with image and text blocks easy to manipulate.
Numbers features a tabbed design and an easy way to link spreadsheets and graphs and to add and update fields. Again, this is all optimized for multi-touch input.
Each app in iWork for the Apple iPad will be available individually for $9.99 in the App Store.