Just installed DevilSpie according to this topic:
The problem is, every time I hit the hot corner, plank disappears. How can I use the specific commands listed in there without minimizing Plank or panel?
You need to tell devilspie to ignore plank and wingpanel. In the minimize.ds file you should have something like:
(if (begin (not(is(application_name) "wingpanel"))) (if (begin (not(is(application_name) "plank"))) (begin (minimize) (quit)) ))
EDIT: I also updated the instructions in How can I view the desktop?, it is quite a nifty feature and I think it should be available in elementary OS by default.