Launchpad in Mac OS Lion shares a key behavior with its iOS counterpart: deleting an app from the launcher also uninstalls it from the computer, as long as the app was purchased from the Mac App Store. Of course, it's quick and easy to redownload the MAS apps if they're needed.
While this insta-delete, complete with jiggling icons, may be counterintuitive for longtime Mac users, it makes perfect sense to iPhone or iPad users where there's a one-to-one mapping between apps on the launcher screen and apps installed on the device. On other mobile platforms, that's not necessarily the case: both Android and Blackberry devices have the ability to hide or subset visible apps versus the full suite of installed programs.
The flip side of this strong linkage between installation/removal and visibility of MAS apps in Launchpad is that non-MAS/conventionally installed apps cannot be deleted from the Launchpad UI. If you don't want all that app clutter, the only default options are to move the space-wasting apps into Launchpad folders (laborious)
or move the apps themselves out of the Applications folder in the Finder (boneheaded, and actually won't work, per commenters). Even resetting your Launchpad (as Erica noted last week) still includes all your apps in the launcher's pages.
There is another way, however, to blank out your Launchpad and start clean. Web developer Loren Segal points out the 'nuclear option' of deleting all the app records from the Launchpad database, which lets you select individual apps to include by dragging their icons onto the Launchpad dock icon (command-click to select multiple apps before dragging). He suggests backing up the relevant database file beforehand, in case of issues, and I concur.
Here's the process in the Terminal, line by line:
mkdir ~/Desktop/DB_Backup[makes a folder on your desktop to back up the data files]
cp ~/Library/Application\ Support/Dock/*.db ~/Desktop/DB_Backup/[copies the database]
sqlite3 ~/Library/Application\ Support/Dock/*.db 'DELETE FROM apps;' && killall Docksqlite3 ~/Library/Application\ Support/Dock/*.db 'DELETE from apps;' \ ' DELETE from groups WHERE title<>""; DELETE from items WHERE rowid>2;' \ && killall Dock
[deletes the app records from Launchpad's database, and restarts the Dock process; you'll see your minimized windows pop back to the screen. Update: Loren posted a new version, as above, that fixes the folders issue.]
Blank Launchpad! You may notice that any folders previously in Launchpad will still be there, albeit vacant. To get rid of them, simply load at least one app into Launchpad, then drag the app into & out of the folder. It will 'evaporate' when it's empty.
If you do decide that you prefer the full-list Launchpad, you can either restore the database to its original location, or follow the tip in Erica's post to reset/rebuild and get all your apps back.