Hey guys! I am new here and I have been grounging around with the 16gb in a 13" 2010 macbook pro issue too. :
Here is what I have found:
My 2010 mbp 13" started its life with 4gb of ram. I quickly purchased 8 and ran into the 1333mhz clockdown issue with the 320m... no biggie, exchanged it for 1066, works solid. Then, browsing ebay, i disovered that 16gb 1066mhz kits are about $54... I jumped on it.
-I was running windows 7 64 bit and os x 10.6. Ram shipped, i immidiately took my computer apart, took it to the garage to give it a blow with the air compressor ( was getting dusty again, especially the fan), and plugged the ram in.
First boot: os x begins booting, freezes. Thats it. **** it
second boot: windows 7 fully boots, all 16gb are visible! great! runs, but freezes after 10 min. Repeat, same issue...damnit!
Reinstalled my 8gb.
So, i read about a recent EFI upgrade, so i got 10.8... so i could do it. Did the efi update.
16gb in, windows begins booting, freezes. crap
mountain lion kernel panic all over the screen. darn.
I took one 8gb stick out, same as above.
Now, this is where it gets interesting. So I thought, ok i ll rma the ram, but before that lets try a 8gb stick and a 4gb stick... bingo.
Os x 10.8 boots no problem, runs stable. windows 7 boots no problem also stable.... So thus, the 2010 mbp is fully capable of 16gb of ram, its now up to apple, to remove the false restriction.
12gb runs FINE. pic for proof.