I like the library kind because it's a single file, and I can add an
icon. I never got the icon to work on bundles. And they tend to behave
like directories (even components from Apple do this!) which is ugly
and confusing.
They will indeed currently show up as folders, this should change (one
hopes) in the future. I've submitted bugs about this long ago. My
(cheap) solution for the time being...just use a custom folder icon
with your shipping component bundle. Once you have your shipping
bundle built, paste on a folder icon and you're done (I said it was
cheap). I also assume the icon you specify in the plist doesn't work
because of a bug but I've never gotten around to file that one.
Someone probably has, or should...maybe even you :)