The iPhone 3GS has very fast javascript performance.<p><a href="http://www.techcrunch.com/2009/06/24/iphone-3gs-javascript-performance-blows-away-rivals-approaches-macbook-speed/" rel="nofollow">http://www.techcrunch.com/2009/06/24/iphone-3gs-javascript-p...</a><p>I don't think I'm making a big leap to speculate that this means the iPhone runs javascript comparably to the consumer-level (read: cheap Best Buy) desktop running some version of IE that most people have.<p>Considering the iPad's processor is significantly faster, I see no reason why web apps wouldn't run perfectly well on it.