One of the new features introduced by OS X Lion is the Launchpad. The launchpad gives you access to the installed applications in your Mac from a window that is reminiscent of iOS devices. In fact, it superimposes on your current desktop window, with a fancy blur effect, and a list of application icons is presented in a rectangular grid. You can even make folder in it by dragging an icon over one other. It seems an iPhone screen on steroids.
In my humble opinion, it's awful.
Anyway, one day, using a wrong gesture, the Launchpad screen was launched and I noticed that the Skype icon was presented twice. Strange, thought I. I tried to remove one of them, but they could not be deleted. I tried dragging one into the trash. It didn't work. To make the story short, I did not lose time investigating this weird Launchpad behavior: it's the kind of window I prefer not to see at all.
Some weeks after Skype informs me that an update is available: I accept to install it immediately and wait for the installer to finish. Curiosity killed the cat: I opened the Launchpad and guess what? Another brand-new Skype icon had just been added to the long row of Skype icons already present in the Launchpad window.
A quick glance confirmed what I already knew: there was just one Skype application installed in my Mac and no other link to it was present whatsoever that might have gotten Launchpad confused. I completely removed Skype from the system and reinstalled it from scratch. No way.
It was just time to act and stop the uncontrollable icon proliferation. Since every user can customize Launchpad, I thought that a good place to start was the ~/Library folder. I grep-ped every file into it looking for the "Skype" string (the icon title in the Launchpad) and a file caught my attention:
An SQLite 3 database file (as confirmed by the file command)! It looks like the potential offender, doesn't it? I then backed up the file, removed it, logged out and logged in again. I started the Launchpad and bingo! Launchpad had just regenerated the database file and now only one Skype icon was shown in the Launchpad window.
As I said, I'm not going to use again. But at least I can rest assured that icons are gone away. Hope this can help you guys if you run into similar troubles with Launchpad.