Some of you are probably wondering, like I did, why some of your applications aren't available in Launchpad. You launch Launchpad and wonder, "Why isn't Microsoft Word showing up in Launchpad?" or "Why isn't Quicken in Launchpad?" or "Why isn't my favorite app that I keep on my Desktop not in Launchpad?" There are a variety of reasons that an app may not appear in Launchpad.
Apps Outside the Applications Directory
Launchpad automatically grabs all applications in your root /Applications directory and in your /User/username/Applications directory. If you keep some of your apps in other locations, they won't appear in Launchpad automatically. To add them to Launchpad, simply drag the app onto the Launchpad icon in the Dock. (Thanks to Eric S for the tip.) Or move the application to your main Applications directory or to your user Applications directory. Or make an alias of it and put the alias inside your Applications directory.
In some cases, it's because the application in question is a PowerPC-only app and won't run on your computer under Lion, which did away with Rosetta. Only apps that are Intel or Universal Binary can run under Lion, and Launchpad only shows applications that can actually run on your computer.
You can tell if this is the case by going into your Applications directory, and looking at the applications icon. PPC-only apps will have a white "NO" symbol superimposed atop the icon. In the screenshot at right, you can see that my Retrospect 6.1 has the white "NO" symbol — telling me that I'll have to upgrade Retrospect or find a different backup program, because Retrospect 6.1 won't run under Lion.
The solution? Unfortunately, the best solution is to bite the bullet and update your PPC apps to newer versions. You could keep a boot drive handy with Snow Leopard on it, and boot from that to run a PPC app. Or you could hack Snow Leopard to make it run under Parallels, but let's not even go there.
Once you update your PPC apps to a newer, Intel or Universal Binary version, they'll appear in Launchpad just like any other application.
Yeah, I know, when it's big-ticket applications such as Microsoft Word, having to spend the money for a newer version bites, especially if you were happy with the old version. But if you're bleeding-edge enough that you've already updated to Lion, you should be bleeding-edge enough to keep your applications more current. I've found that it's generally a bad idea to get more than one version behind with any of my important applications. I might skip a version, but then when another version comes out, I go ahead and upgrade. Then when I get a new computer or a new big-cat operating system, the upgrade isn't quite so painful.
In other cases, it's because the app in question is a Windows app that you use under Parallels or VMWare. I couldn't wait to stop Launchpad from showing me the gazillion Windows apps in my 3 Windows installations under Parallels, but you might want the opposite.
The solution is to go into your virtual machine configuration, Options -> Applications, and check the box to "Share Windows applications with Mac."
You might find that your application is located in a subdirectory inside a subdirectory inside a subdirectory in your Applications directory. If that's the case, it's probably in some random application "group" that Launchpad helpfully created for you. If the app is in an application group in Launchpad, you don't have to physically move it around in your Applications directory; you can simply go into Launchpad and drag it out of the group.
Update: Or you can simply drag the app onto the Launchpad icon in the Dock, and it will appear in Launchpad. (Thanks to Eric S. for that tip in the comments below.)
Or you can make an alias of the app and put that in the top level of the Applications directory. Then the alias will appear in Launchpad just like any other application.
Did I Miss Any?
Are you aware of any other instances when an application doesn't show up in Launchpad? If you are, let us know by using the comment box below their website.