It'd be cool if the stand is designed so that we can use the device in upright position during daytime and folded down to act as HUD for night use (less bright, better visibility)... and the device also knows which mode to use by time\orientation\light sensor and switches its mode accordingly.

Obviously this can be extended to include other informations than just navigation data (but not to be overburdened with unnecessary info...).

seems kind of silly to me, why not just look directly at the device?

I have the HUD from the factory in my 2002 Grand Prix GT and I like it a lot. I really think all cars should have this feature standard, especially for new drivers. My windshield is like $200 more expensive though, if I ever have to get it replaced because of the interior reflective coating but you can see it in the day.

In fact I've got the idea about a HUD app while I was driving the other day, but I realized that it won't be any good during the day. A real HUD has no issues with that, I think:
http://antzinpantz.com/kns/images/hud.jpg

bumb.
i came up with the same question about HUD
i did the search first and found this thread. i think Jspeed works fine even i daylight but it doesn't have option to rotate the image so that can be seen from windscreen without reflection being a mirror image of original jSpeed display... sry for bad english, i hope you get the point
So i was wondering could it be possible to add such option to jspeed or some similar app?

Speedometer
http://store.ovi.com/content/46015