As a user I've long been annoyed by the current Facebook iOS App (especially on my original-model iPad.) As a developer I've also been disappointed by what a poor example of an HTML-based mobile app Facebook has provided. Hacker News has a post today which links an article called Here’s why the Facebook iOS app is so bad that explains why.
Among other interesting commentary on the Hacker News post, is a link to an article by LinkedIn about LinkedIn for iPad, that provides some details about their architecture. If you haven't tried the LinkedIn app, it's worth looking at -- if only to cure the feeling of sadness you get from the Facebook App.