We really like Gist, and now I've got some even cooler news: There's a Gist iPhone app as well.
Gist has just shown up in the App Store for the relatively low price of free. The interface is similar to what you get on the Web; there's a dashboard that aggregates news, blog posts, and tweets for the people and companies in your network of contacts, and a Share button makes it easy to email any of these items to someone else.
You can also drill in for detailed looks at contact information, email attachments, and recent emails. The app retains one of Gists's trademark features; its ranking of the relative importance of your various contacts, which lets you triage your attention in a logical way.
I've been using Gist for about a week, and I'm still sizing it up, but already the Gist iPhone app has significantly increased Gist's value to me. It's definitely worth checking out.