First, the caveats:

1. Measurements may not be 100% precise, but I pretty definitevely vouch for the relative scale in so far as if I said one measurement was bigger than another, then it was. Don't go after me if I'm off by an eighth or two here and there.
   
2. I only measured two seats on the upper deck, but a quick look at the others suggested that they all followed the same pattern and measurements.
   
3. I did measure several seats on the lower deck, *except* for the row 9 and 10 seats which I was only able to visually observe. I'm pretty confident in my measurements here.
   
4. All pitch/bed length measurements were down the middle of the seat/bed.

Now, the overall findings.

1. There are 11 different types of seat. This is absolutely astonishing.
   
2. All the seats are in pairs, and in each pair, one seat is about an inch better off than its partner, both in terms of seat pitch and bed length. This is always the right hand seat, in a pair that angles to the right, and the left hand seat in a pair that angles to the left. The reason is obvious - the seats are at a slight angle, but the center console is straight.
   
3. As the hemispheres photos earlier in this thread showed, there is a difference in the centre armrest to IFE console gap. On the upper deck, this gap is 9.75". On the lower deck, this gap is 14.75".
   
4. The above does NOT translate in itself to a greater seat pitch. All seats have either a 54" or 55" sitting pitch. This measurement is taken from the front of the seatback (i.e. where your back rests when sitting) to the end of the footwell.
   
5. There are two factors contributing to #4 above. Firstly, the center console is thinner on the lower deck. I couldn't figure out what was going on with my measurements until I realised my shoes almost fit in to the console on the upper deck, but were not even close on the lower deck. The cushions for your feet are the same length in all cases, but measured at the floor (where you would store your shoes), on the lower deck the footwell in the console is 8.75" deep, and on the upper deck it is 11.75" deep. Well spotted, GadgetFreak!
   
6. The second factor, quite shockingly, appears to be the length of the seat bottom cushion. Unfortunately, I failed to measure this upstairs (because I didn't think it was going to be relevant), but I did notice that my table was a little closer to me downstairs, and visually I think this is where the other 2 inches of difference comes from. The telltale sign was the position of the lines of stitching on the cushion. Extremely odd, but them's my findings! Someone else will have to verify to be sure, but this seems to be where the other two inches come from. The lower deck seat bottom cushion was 20", so I'm predicting around 22" upstairs. It may also be worth measuring the armrests upstairs - 16" long on the lower deck, and I suspect 18" upstairs.
   
7. All seats on the upper deck are angled to the right. On the lower deck, half the seats, specifically seats 6CD, 7CD, 8CD, 7AB, 9AB, 6JK, 8JK, 10JK all angle left.
   
8. Although the width of all seats with armrests down, as measured from edge to edge on the armrests, was 23.5", as advertised, there is a significant width difference that is not mentioned. In some seats, the armrests are fully within the seat shell, but in others, the armrests actually go wider than the shell. What this means is that your shoulder width also differes from seat to seat. Just to make it more exciting.
   
9. The difference in bed length between the shortest and longest seats was really noticeable. A world of difference for anyone over 6'1" I'd say.

So with all that, it boiled down to three key variables on each seat. The bed length, the shell or shoulder width, and the direction faced. In truth, there's also the footwell shapes as half the footwells have a height restriction which will impact you if your feet are above a size 10 and you want to have them pointing upwards.

Unfortunately, I failed to note down exactly which ones are which way, so for fear of misleading people on that score, I won't say anything at all.

And without further ado, here's how the seats break down. Measurements are in the order of bed length, shoulder/shell width, and direction facing (R = rear, F = forward):

1. 78", 23.75", R -- middle seats 6D, 6G, 8D, 8G
2. 78", 23.75", F -- aisle seats 7C, 7H
3. 78", 22", R -- aisle seats 7B, 7J, 9B, 9J
4. 78", 22", F -- aisle seats 6B, 6J, 8B, 8J, 10B, 10J
5. 77", 23.75", R -- no seats matching this criteria
6. 77", 23.75", F -- middle seats 7D, 7G
7. 77", 22", R -- window seats 7A, 7K, 9A, 9K; aisle seats 6C, 6H, 8C, 8H
8. 77", 22", F -- window seats 6A, 6K, 8A, 8K, 10A, 10K
9. 75", 23.75", R -- window seats 13A, 15A; aisle seats 13J, 15J, 17J
10. 75", 23.75", F -- window seats 12K, 14K, 16K; aisle seats 14B, 16B
11. 74", 23.75", R -- window seats 13K, 15K, 17K, aisle seats 13B 15B
12. 74", 23.75", F -- window seats 14A, 16A; aisle seats 12J, 14J, 16J

Yes, ladies and gentlemen, there are 6 seats that are the longest and widest beds on the new 747-400 in business class, and 4 of them are MIDDLE SEATS!!!

If you're like me, and you're about 6'3", need the lie-flat to be rear-facing to sleep well with the bed flat, and like to be by the window, you're pretty much out of luck. Ouch.