well, the dot in the bottom left of the viewfinder goes green when it's locked, NOT the AF point itself (unless I'm missing something). It's pretty similar to canon in that regard, EXCEPT Nikon has arrows on either side of the dot showing you which way the AF is off. These arrows also work in manual focus which can be VERY helpful. The one beef I have is with single shot mode, you can set it to fire on focus or shutter priority. Shutter means it'll shoot if it's focused or not. focus priority means it'll only shoot if it's locked. I like "one shot" with canon's with the beep on, but with the rear button running AF. Release the rear button and you can fire OOF shots on a 5D all day if you want BUT it will beep when it's focused. With the D700, if you set it to shutter priority you can still take OOF shots if you like, but the beep only works in focus mode meaning it WILL NOT FIRE unless it thinks it's locked.
My issue with this is there are times when I'd rather have a slightly blurry shot but get the shot than to have it not shoot because it thinks it's OOF when in fact it's only slightly OOF... But I also like the beep. WIth the nikon I can't have the beep and the ability to take OOF shots. I've been living w/o the OOF shots.
but with the nikon you CAN choose shutter AND focus. In that mode it will pop off ONE shot regardless of lock or not, then a SECOND once it's got the lock which is pretty sweet.