So I bought an iPhone. After being tortured with a BlackBerry that I could never get to work right, I think I deserved it.
It definitely is a cute toy, but my real justification for buying it is business. Having recently gone into business for myself (developing websites - if you need somebody, I'm your guy :),) I needed a tool to stay in touch with clients as much as possible. I also wanted something that would allow me to deal with emergencies, without constantly dragging a laptop around. I hoped the iPhone would allow me to make minor edits and possibly restart a server.
So does it live up to expectations? It does. There are two amazing apps that make the iPhone an icredibly useful business tool. Every web developer and server admin must have them.
The first is ezShare (on iTunes here: link to app) This app can connect to an FTP server, download files to your iPhone, and edit ASCII files. For emergency fixes it's great. The support provided by the developers was excellent, my emails were replied to quickly and intelligently.
The second is Jaduu RDP (available on iTunes here: link to app) This app simply blew me away. You can login to your windows server and it does a very effective job of giving you a very usable UI on the tiny screen. Great if you are need to restart or diagnose issues.
I also use the iPhone to read (and write!) blogs, keep track of my finances, scan barcodes (with an app called RedLaser - very cool,) chat & IM, and follow my favorite teams. Overall, it's a great combination of business tool and fun toy.