My speculation is KL: S and B, booked into D

In many of the markets it's offered from, D class (discounted biz) on OK is cheaper than (not just Y but also) M.

Where are you seeing that DL does not participate? They are actually used as one of the examples in the press release announcement and there seem to be details about booking class and purchase class for them.

For AF: Y/B/K (and H in Japan, and T in New Caledonia) to O in Biz
For AF: J/C/D to A in First
For KL: Y/S/B to D
no First on KL

For DL, I know that it is written on the press release but it is not mentioned on the AF communication to travel agencies.
And of course I have no code.
So, these are the rules for AF/KL Flying blue members.
There are probably different rules for others skyteam FF programs.
Hope it helps you.

This mileage upgrade program seems to be much more restrictive than what everyone is posting. I think the disconnect may be that some are posting what their own frequent flyer program offers as upgradeable fares, whereas the Skyteam Mileage upgrade program seems to be truly FULL fare economy.

NW offers its own frequent fliers upgrades with Y/B fares. Delta Y/B/M fares, KLM Y/S/B and AF Y/S/B/K. However as an example, when I look at the following NW chart, NW fliers can only upgrade AF Y fares, not Y/S/B/K like Flying Blue members:

Skyteam parner upgrades for NW:

SkyTeam Carrier Marketing and Operating Code Eligible Full Fare Booking Classes:

Aeroflot SU S, Y
Aeromexico AM Y
Air France AF Y, S
China Southern CZ Y
CSA Czech Airlines OK Y, M
Delta DL Y
Korean Air KE W, Y

Alas, at these fare levels it is usually cheaper to buy a discounted business class fare than use the miles to upgrade. Then again, it might be a advantageous for last minute travel.

As an add-on comment for this thread-- the Skyteam upgrade program is truly FULL fare Y class. I recently booked a Y fare international ticket with DL and after 20 min on hold with the NW Platinum line, they told me I could not use Woldperks miles to upgrade the DL ticket because it was an international Y fare that was not classfied as "FULL Y" fare.

That points out part of the joke of this program-- the domestic segments on DL were already upgraded at time of ticketing because it was a "Y" fare but yet I could not use NW miles to upgrade the international segments under the Skyteam program because the ticket was not FULL Y.

Since DL upgrades Y/B/M tickets under its Skymiles progam, I could use miles I have on that account to upgrade my Y fare, ut but then I don't want to lose the NW miles collection and EQM collection when others tell me I will lose that benefit if I pay the miles with DL.

So at the end of the day, my million plus NW miles are still worthless, because I cannot use them to upgrade a Y ticket and don't want to risk losing the EQM by using DL Skymiles for the upgrade since I am told I will then earn Skymiles EQM instead.

Has anyone had success with this program? I am considering a trip to EZE on AM and Delta tells me I need to call AM and they will call DL to process the UG. That doesn't seem right to me. The rep also told me it is only 10,000 miles each way to UG NYC-EZE of AM full Y which also seems too low.

Has anyone done an upgrade from biz to first on KE? How is it done?

AFAIK the ST upgrade program applies only for Y -> C.
Also I think that First awards in general are only for members of the home FFP. (AF might have a special agreement with KE though, but not for upgrades.)

That's what an FB agent told me, but he seemed pretty clueless about it so I wanted to double check. Maybe I'll trying calling KE directly and see if there is a way. I'm booked in biz on the KE A380 LAX-ICN but I'd love to try F.

The SkyTeam Mileage Upgrade Programme does indeed seem to be limited solely to upgrading economy to business:
As a SkyTeam frequent flyer you can use your Miles to upgrade from Economy to Business Class on international flight itineraries on most of the SkyTeam Member airlines (Aeroflot, Aerom�xico, Air France, China Airlines, China Southern, Czech Airlines, Delta Air Lines, KLM Royal Dutch Airlines and Korean Air).

See this thread for my recent experience of using FB miles for a Y->Z upgrade on KE.

I hope you manage it!