Q: I have a third-generation iPod touch and am considering buying an iPhone 4 in the next couple of months. Will I be able to transfer my apps from my iPod touch to my iPhone? How is this to be done? Thank you.
A: Absolutely, and the process is almost automatic. Sync your iPod touch to your computer one last time before setting up your iPhone and then be sure to setup your iPhone 4 using the same iTunes library. When you first connect the iPhone 4 it will ask you whether you want to set it up as a new iPhone or restore it using a previous backup.
Simply restore the backup from your iPod touch onto the iPhone and all of your settings and application data from the iPod touch will be restored onto the iPhone, including the settings for iTunes as to which content was being automatically synced to your device. iTunes will then proceed to reinstall all of the applications that were on the iPod touch as well as any music and other media content you were previously syncing to it.
Note that this is a one-time process. If you plan to continue using both the iPhone and iPod touch you can certainly use the same applications on both devices but there will be no way to regularly transfer or sync data between the same apps on different devices unless the applications provide their own synchronization features.