In order to win the team gold in a Chess Olympiad, the winning team must have exceptional performances by at least 2-3 players and a decent performance by at least 1 (or 2) other team member. In this case, even if one player has not so good results, the rest of the team can carry the match.
Let's examine the individual records of Ukraine and Russia (w).
Ivanchuk and Efimenko had fantastic individual records and they both won individual medals (Gold for Ivanchuk and Silver for Efimenko). In the mean time, Ponomariov and Eljanov had decent individual performances, just a tad below their ratings, but over 2700. In the case of Eljanov, even with a slightly below par performance, it was good enough for an individual Silver medal as well. Therefore, in spite of a poor performance by Moiseenko, they won team Gold.
Russia had 3 exceptional performances by the Kosintseva sisters and the youngster Gunina. Both Kosintseva sisters won individual Gold medals. Gunina would have won Gold but she was one game shy of meeting the requirement. They basically carried their team. Galliamova also had a good performance, a little better than her rating. Therefore, in spite of a sub par individual performance by Alexandra Kosteniuk, Russia crushed the rest of the field for Olympiad team Gold.
Another factor is board orders. This is so important in Chess Olympiad competition and personal ego should be checked at the door. This is also why strong teams need strong captains and not political or sponsors' appointments.
Ukraine placed Ponomariov on board 2 even though Eljanov is slightly higher rated. This was an excellent move as Ukraine came away with Gold. Ivanchuk redeemed himself after the last round melt down in Dresden in 2008. Is he getting stronger and better with age? :)
For Russia, Kosteniuk's willingness to play board 3 (unprecedented move as no reigning WC or WWC has ever played board 3 in Olympiad history) paid off big time for Russia. But this was a smart decision and she deserves a lot of credit for doing this. With Kosteniuk on board 1, T. Kosintseva on board 2, and N. Kosintseva on board 3 in 2004 Calvia, 2006 Turin, and 2008 Dresden Olympiad, Russia did not win. But in this Olympiad, they won all matches and dominated the field with T. Kosintseva on board 1, N. Kosintseva on board 2, and Kosteniuk on board 3.
There are many more little factors which contribute to teams' success in a Chess Olympiad but above are some important ones.
For these teams, they have got a strong and large pool of players to choose from unlike Malaysia, where the choice is limited by choice or pool, until and unless MCF change for the better, we will see the same results year in year out. Monetary benefits especially playing as professionals is a major boost in success.