Every now and then, a UI concept is so good that it becomes contagious in fascinating and frustrating ways. I’ve run across two recently.

The first is the iPhone touch screen. A few months ago, when I first got my iPhone, after playing with it for about 30 minutes, I went back to work on my mac, and my fingers automatically expected things like the two-finger zoom to work. I was stunned. Not surprisingly, that is now a feature of the new Macbook Air, and I expect it’ll be in all mac laptops.

The second occurred to me this morning. I was using ssh (a command line tool) to log in to a variety of machines with cryptic addresses, and I knew that I had to start looking for a place to write down those username/hostname combinations. At the same time, I realized that what I really wanted was the awesomebar for my terminal window. The notion that “the computer” should just remember what you’ve done no matter where, because past behavior is the best predictor of future behavior, and that we can implement that quite well with simple mechanisms like keeping a history and doing some math on that history, is a contagious idea. (Note to unix weenies: I know that with the right magic i can get some pseudo-awesomebar within bash. Not good enough! I want bookmarks, tags, weave!)

Naturally, it applies to Thunderbird as well. I routinely go back to “the same” emails. We should find a way to make that as obvious and invisible as Firefox 3 does for web pages.