The concept of attaching a file to a file to an email is practically as old as email itself. With the iPhone, you can attach photos and videos to your email, but that's pretty much where the fun ends.
This works fine for stock iOS installations where access to the native file system is restricted. For jailbroken iPhones, however, it's a definite limitation; hence the need for a jailbreak tweak like AnyAttach.
AnyAttach is a tweak that allows you to attach any file present on iOS's file system, directly to your outgoing email...