Uh yes it does. Rendering desktop icons uses ram and obviously it loving worked if it freed up ram space. Stop trying to act as if you're a loving know it all and that you need to prove me wrong at every opportunity.
Actually, rendering desktop icons does use very little RAM. Just as much as opening a folder with a bunch of stuff in it. The reason your PC went from 1.8 GB of RAM to 1.2 when deleting stuff is because it had to use that RAM to transfer files over to the recycle bin and delete it. Again, I know this because my RAM got raped when I tried to delete a bunch of videos I took of Blockland (well over 4 GB). Plus, there's a lot of cached stuff in the RAM, probably.
Plus, you're probably using Windows Vista or Windows 7, so of course it's going to use a bunch of RAM. It's a modern OS, there's plenty of RAM, it's going to use a bit of it until it has to give it up for other programs.
Basically, what I'm saying is, it's not a virus or anything, nothing to freak out over.