I like when it opens in a new tab, I always open links in a new tab anyway, so when I forget to middleclick it's very frustrating to discover on closing a tab, that I am not brought back to the source of that tab.
Slashdot is an example of things that don't open in new tabs by default, so when I forget to middleclick, I end up losing my position in /. also. very annoying.
