Multiple iPhones, iTouchs - buy multiple copies of same app?

I will getting another iTouch and want to have some of the apps I have on my current one. I assume that I'll have to buy additional copies or does it depend on the app? If not, I assume it's just a syncing thing I have to do to get it on the new iTouch. Thanks in advance.

As long as your Ipods are synced to your computer you'll be able to use the applications and music that is protected. No problems at all. I've only had real troubles with my Nano (4th Gen) and Shuffle (2nd Gen), when hooking them to other computers just to charge with Itunes running. The Nano suffered a HDD failure and a restore was neccessary, and the shuffle deletes all the info and has to be reformated and mated to my Mac again. That pushed me to buy the wall charger, instead of using the computers at work to charge it. From then on I have a huge rule about hooking any of my ipods to other PC/Macs. Its just not worth the trouble.