I’ve been using the iPad 2 and the Apple TV to mirror content on the iPad to a LCD projector in my classroom. Overall, things work great, but there are two shortfalls.
1) If you have a widescreen TV or LCD projector, the iPad won’t project Keynote presentations (or create or edit them) in widescreen format. The desktop version of Keynote has adjustable settings for size of screen. Interestingly, video (both on the iPad and Netlix) automatically scale to widescreen.
2) You cannot annotate a presentation in Keynote. This is one of the major selling points for interactive white boards and either their proprietary software, or in the case of SMART Technologies, their interaction with Microsoft apps (e.g. PowerPoint). When Keynote for iPad allows for annotation, the entire interactive whiteboard industry will be doomed. It seems that Apple was planning this feature, but as of yet has not enabled it. See the link below:
Otherwise, Keynote for iPad works great, and in my opinion, it’s easier to work with presentations via multi-touch rather than a mouse.