iTunes has the ability to update the carrier-specific settings on iPhone and iPad Wi-Fi +3G. Carrier settings updates are small files (about 10k) that are downloaded from iTunes to be installed on your iPhone or iPad Wi-Fi + 3G. The carrier settings can include updates to the default APN (how the device accesses the carrier’s cellular data network).
The carrier settings for iPhone also include special dialing codes at Settings > Phone > [Carrier] Services, default settings for Stocks, Maps, Weather, and other items.
It is recommended that you install these updates to your iPhone or iPad Wi-Fi + 3G as soon as they are available.

iPhone Software 3.0 allows you to see if Call Forwarding is enabled by displaying  in the status bar:

In rare instances, this icon may not appear after turning your iPhone off and on, even though Call Forwarding is still enabled.

This document describes the security content of iPhone OS 3.0.1.
For the protection of our customers, Apple does not disclose, discuss, or confirm security issues until a full investigation has occurred and any necessary patches or releases are available. To learn more about Apple Product Security, see the Apple Product Security website.
For information about the Apple Product Security PGP Key, see "How to use the Apple Product Security PGP Key."
Where possible, CVE IDs are used to reference the vulnerabilities for further information.
To learn about other Security Updates, see "Apple Security Updates."

If you’re having difficulty syncing your contacts or calendars to iPhone, iPad, or iPod touch with iTunes for Windows via USB, this article can help. Note that this article does not apply to wireless syncing with Exchange ActiveSync or MobileMe.

iPhone and iPod touch have an internal rechargeable battery. To charge the battery, choose one of the options below:

Connect the device to your computer (not your keyboard) using the included cable to charge the battery and sync. Your computer must be turned on and not in sleep or standby mode. If the device is connected to a computer that’s not turned on or is in sleep or standby mode, the battery may drain.
Connect iPhone or iPod touch to a power outlet using the included cable and a USB power adapter to charge the battery.

Note: iPhone 3G, iPhone 3GS, iPod touch (2nd generation), and iPod touch (3rd generation) do not support FireWire and will not charge from any FireWire-based power source.  If you connect either of these devices to a FireWire-based charger or accessory, you will receive the alert screen below:

"Charging is not supported with this accessory."