Discuss HN : Best practices for offline caching in iphone.

I wanted to pick brain on some of the architectural issues in creating an iphone client app for a reasonably complicated REST style web application, example a twitter client. Here are my specific questions

1) In practice, Do we need caching at all ? 2) How will you go about implement caching ? Simply cache {URL}=>{Content} values, or replicate the schema in sqlite3 and cache things there. 3) Are there specific issues in dealing with profile images, especially when you have to show a lot of them on a single page.

Thanks,