The iPhone is a great little device, but there is room for improvement. Hopefully with Apple’s big event on Wednesday we’ll see an announcement about the iPhone 4.0 OS. TUAW has put togther a set of things (part 1, part 2, part 3) they’d like to see based on user submission, and there are a lot of great ideas. I’ve got a few of my own ideas that I’d like to see as well. While there is likely to be a new hardware version of the iPhone coming out this year, my focus right now is only on the OS. Why? Because I won’t be getting a new handset for at least a year. 
Home Screen – The home screen is nice, but a bit simple. Organizing has gotten easier with the improvements to iTunes, but it still takes forever to get from the first screen to the last.
I tend to organize each screen based on genre, but I think it’d be cool to have the ability to say “only show me games or social apps”. Even if you could type in the genre into spotlight to get the list. i.e. app:games
One last thing on the home screen, I use my iPhone most of the time in landscape. It’d be cool, and I’m guessing pretty easy, to make the apps rotate based on the phone.
Messages – Push notifications are nice and I use them often. Though if you get a few push notices, a phone call or two, a voice mail, and then a few text messages you tend to lose those notices. There is a message app already used for text messages, put another section into it and have it display all your push notices. That way, if you get multiple you can see them in one easy spot.
Web Browser – Safari isn’t bad, but it could use some sprucing up. Of course the big thing here most people want is Flash. I hate flash, but there are still a lot of websites out there that use or require it. I spend 95% of my non-work Internet time on my iPhone… it needs Flash. Period.
The auto reload when you switch between tabs is annoying. TUAW suggested adding a configuration option to disable that, and I agree!
Photo Album – You only have one photo album on the iPhone. That sucks. I’d like to have more, so I can better keep things organized and have easier importing when I hook it up to my Mac with iPhoto. Wireless syncing of the iPhone and iPhoto would also be sweet… of course, Apple could always wireless sync everything (apps, music, movies, etc.).
That’s pretty much my list. Though like I said, read over the TUAW articles. They cover a lot, and I’d have to agree with most of the features. Hopefully we’ll see some big news in a couple of days.