I have just reinstalled my Air with Lion. I didn't want to do a Time Machine restore, as I really didn't want any of the old apps, and I'd like to manually sort through my home folder and discard old crud.
After copying back my previous hard drive contents to ~/PREV, I noticed that Spotlight would suggest to launch apps that existed there, even though I hadn't "installed" them, like copied them to the /Applications folder or run their installers (for those that have them).
I quickly updated the Spotlight preferences to not index the ~/PREV folder (no need to, anyway, as it was only a temporary folder). That fixed that.
Now, I just discovered that Finder has context menu items stemming from BetterZip, which is now in my Downloads folder, having been copied over from my PREV folder. I did not install BetterZip.
What the ....? Somehow OS X is automagically installing .app files whereever it finds them? How on earth is this a good idea? What is OS X doing behind my back? And most importantly, how do I stop this crazy behavior?