I'll add another feature suggestion. I frequently use the iPhone to add a series of simple todos (think shopping list). It would be great to have something like the Multiple Tasks view in the web app. Basically a big text field where I can put one task on each line and have them all go into a folder.
First make sure you are running the latest version by going to Settings->About. It should be version 1.5.3.
If so, you should have three different settings in the app under General, the third being landscape. I can't imagine the iPhone OS 3.0.1 update would have changed anything since it was only an SMS patch, but I can't say for sure because iPods, like mine, didn't get that update.
I checked and, sure enough, the version was 1.5.2 -- even though I'd been using 1.5.3 and enjoying the landscape before it inexplicably went back to 1.5.2.
And App Store said all my apps were up to date... so I deleted and reinstalled the app. Presto.