Strange- this issue dates back to at least snow leopard for me. I remember thinking it was tied to my setting the screen saver to lock the screen/slow disk. I live with it but would love to see it fixed.
For me this is a new MBP with an SSD. With Lion I could open the lid, immediately type in my password, and be back on wifi instantly. It was probably my favorite thing about the machine. Now waking up has become rather frustrating. I'm considering going back to Lion until this is fixed.
