I've previously posted links to the more than 100 new features in iPhone Software 3.0. The obvious new features are, of course, some of the best. Copy and paste and search, for example, are stand out new features. But you have probably already read about those new features, so here are a few tips regarding the new iPhone operating system that might not be so obvious. [UPDATE: Click here for a newer post with even more tips and shortcuts.]
Battery drain solution. I noticed after upgrading to 3.0 that my iPhone battery life became horrible. I also noticed that my iPhone was warm to the touch, a sign that there was constant activity on the device. After searching through Apple's support forums, I discovered that many others who used push e-mail on the iPhone (Microsoft Exchange or Yahoo! Mail) had the same problem. The solution was simple: Go to Settings --> Mail, Contacts, Calendars and then select your push e-mail account, which for me was my law firm's Exchange account. Then tap the red button at the bottom that says "Delete Account." After a few minutes, the account will be deleted. Then choose "Add Account..." and setup the account again from scratch. It only takes a few minutes to download the e-mails, contacts, etc. and once this is done, the iPhone works normally with no battery life problem. Apparently, when upgrading to 3.0, something wrong happens on some iPhones to cause the iPhone to constantly think that new information is being pushed to it, which wears down the battery life. But once the account is deleted and then restored, the problem goes away. Whew!
Turn off the shake. By default, when you are listening to music on the iPod app, a shake of the iPhone will cause the app to go into shuffle mode. This is a neat party trick, but frankly not something I plan to use a lot. And to the contrary, I don't want my iPhone to start shuffle mode just because I accidentally flicked my wrist. You can turn off the feature by going to Settings --> iPod and then turn off Shake to Shuffle.
Sort your search results. You have probably already noticed that if you swipe the first page of your home screen, there is a search screen to the left that allows you to search across multiple apps on the iPhone. What you might not know is that you can choose the order of the search. If you commonly use this feature to search your e-mails, you might want to have e-mail searches come up first. For me, I commonly use this feature to search by app name and then jump to a specific app, so I want app names to appear first. To change the sort order, go to Settings --> General --> Home --> Search Results and then use the icons on the right side to move the results up or down. You can also uncheck categories if you don't want search to take the time to look through one of them.
Find my iPhone. If you subscribe to Apple's MobileMe service -- which normally costs $99 a year but if you click here you can get it for only $74.99 through Amazon -- you can find your iPhone if it is lost. But you can't use this feature unless you first turn it on. Go to Settings --> Mail, Contacts, Calendars --> MobileMe [or whatever you have called your MobileMe account] and then turn on Find My iPhone. Speaking of which, I encourage you to click here for a thrilling story about a man who tracked down his iPhone from a thief. I don't encourage you to put yourself in harm's way by taking justice into your own hands, but it is a good story, and as Jason Snell notes on Twitter, it is probably the first of many such stories that will come out of the new Find My iPhone feature.
30 second rewind. I often listen to podcasts on my iPhone. Sometimes I am doing something else at the same time and my attention is not on the podcast when suddenly I hear something interesting being discussed. With the new 30 second repeat option, you can just tap the button near the top of the screen and instantly rewind the last 30 seconds. It is a fantastic feature that now seems so obvious in retrospect. And speaking of podcasts, the new ability to change the FF and RW speeds by moving your finger up and down the screen is very useful.
Force quit. You used to be able to force quit an app by holding down the Home button for about 10 seconds. That doesn't work any more (because the home button is used to trigger voice controls on the new iPhone 3GS) and the new shortcut is to hold down the sleep/wake button until the slider appears, and then hold down the home button for about 10 seconds.
I'll post more about 3.0 as I have more time to use it. In the meantime, if you want more of the nitty gritty details of iPhone Software 3.0, check out this great article from Macworld's Dan Moren which details many new features that Dan came acorss while preparing Macworld's review of 3.0, and check out this post on the MacRumors forums. Also, I would love to get an e-mail from you or see your comment on this post if you want to share some of the 3.0 features that you find the most useful.