iPad: Last week Apple released a version of iPhoto for iOS, but it's only compatible with new devices like the new iPad and the iPad 2. However, if you want to get the app installed on an unsupported, first generation iPad, iPhone blog AppAdvice shows it's pretty easy to do and doesn't require a jailbreak.
You'll need the $5.49 iPhoto app downloaded in iTunes and the free iPhone Configuration Utility to do this. The process is incredibly easy and after testing it out on a first generation iPad the iPhoto app appears to function just fine as an image editor and management tool. Theoretically, this could work for other apps that don't technically support the first generation iPad. Hit up the full tutorial over on AppAdvice for a walkthrough of the process.