Starting out?

Ten pockets on a c.15 litre rucksack? Sounds more like a collection of extra-small stuff-sacks than a rucksack, Ross!

I don't think you'll find that. Some of the Osprey packs have quite several pockets, but you're not likely to find anything like 10.

What's it for? Would some kind of fishing bag or military piece of kit do the job better?

Clicky...

(but sit down to look at the price)

Scary A little saner price wise - Rohan. They actually had two previous styles in the Souk (and thus cheap) but only one left and thats extra small.

Suppose we may need to define pockets  

If he means/accepts internal pockets then its probably quite easy to get close, especially if they don't have to be enclosed. Various life style things.

If mesh counts then most MM sacs are of course not all that far off 2 hip belt + 2 side mesh + front mesh + lid pocket + main compartment. Stick a chest pouch or something on extra and you're there

military or ambulance/first aid pack. neither are cheap!

could try Orvis (fishing people) or carp fishing stuff.

is it for  anything particular?

Military style bags tend to have lots of pockets, maxpedition and some of the other makes at Heinnie might be worth a look on that front.

http://www.heinnie.com/Bags-and-Wallets/c-1-281/

http://www.heinnie.com/Bags-and-Wallets/Oakley/Oakley-Bags-Tool-Pocket/p-281-865-6887/

http://www.heinnie.com/Bags-and-Wallets/Hazard-4-Bags/Hazard-4-Bags-Evac-Photo-Recon/p-281-776-5751/

http://www.heinnie.com/Bags-and-Wallets/Hazard-4-Bags/Hazard-4-Bags-Tonto-Mini-Messenger-/p-281-776-5422/

http://www.heinnie.com/Bags-and-Wallets/Kata-Bags/Kata-Digital-Rucksack-DR-465-/p-281-347-2599/

just throwing a few ideas from imo one of the best sites out there