Well, it looks like "They" are bringing back overalls for Spring 2010. All I can think of is the years between 1995 and 1997 when I was pregnant with my boys and I wore them to death! I'll never forget my fashionista sister Kate saying, "Would you stop wearing those damn overalls all the time!" or something like that. They were good maternity and post-partum wear though.
I can see wearing the Ralph Lauren look (first pic above). I think with a fitted top underneath and either a bit of height in the heel of a bit of ankle to keep from looking too boxy, it can be a cute look. Just might take a while to trickle down to the masses!