It may help if you change out your p.steering fluid with a good synthetic which will stay fluid at cold temperatures better than the regular oil.
How-to here.

 

I have a van with a 5.4 and my cold weather noise was the A/C compressor (I was leaving it on defrost). I isolated it by doing the belt trick (take if off for the night). Oddly, I noticed my SuperCrew does not engauge the compressor right at startup, but it has a noise from the ps pump (just like the other posts here).

The belt installation was a PIA at 6 AM in the cold, even if it did only take a few min. I was nice to know it wasn't the engine though. Well, I should qualify that - it was nice to now that the piston slap was the only engine noise, and not this other weird noise.

A funny side note my neighbor's Chevy refused to start a few days ago (5 degrees outside). I gave him a ride in my Ford. We jumped in my van and fired it up cold. The A/C racket came first drowning out the piston slap. Then you could hear the slap. He looked at me as if to say "what the hell was all that". Before he could start to say anything, I just pointed at his truck and said - "at least mine runs". I don't really get into all of that Chevy vs Ford stuff (his truck is very nice), but it was a cool moment.

 

I have the 4.6L engine, and I get that same noise. Only when the temperature is well below freezing as it was last night at -40.
I have a block heater and the truck is plugged in all night and I find that it helps to lesson the duration of the noise. Scares the wife who sometimes thinks the truck is going to quit.

 

HI!... I have REDLINE synthetic D4 fluid in my P/S pump and it still gets the 1 second WHINE on start up in the morning. So sythetic fluid will not help in cold weather.

 

Hmm... so much for that suggestion. Thanks for the heads-up. I used the Mobil1 synthetic mercon in mine.

 

I have the problem also. I just turn the wheel as the truck starts and it is gone, just a little whine left. But it has to be below 0 like 5-10 below.