Mikey / rickity :
Microsoft OS without a Recycle bin ( i.e. DOSes and early Windows versions ) do that - mark a file as deleted, and the space is overwritten on an as-needed basis.
Recycle bins work slightly differently, in that the file is sort of marked as deleted, but the space is kept until all the truly free space is gone. I'm not so sure of the exact algorithm used, but it's a tad more intelligent.