http://www.myfantasyleague.com addressed the McCardell incident thoroughly, and the rule stands for all turnovers.
I don't know how Yahoo! will score it, but if you are the commish of a league you need to check that QB, RB, WR's, etc. are given credit for things like 'offensive fumble recovery returned for a TD' or your player won't get credit for the TD. Similarly, K's should be credited with passing, rushing and recieving stats as well in case they are involved in a fake FG attempt, etc.
This is the McCardell discussion:
Some leagues think that this should be considered a defensive touchdown, because they say that once a change of possession happens, the team that was once the offense is now the defense, and vice versa. Therefore, should this be considered a Tampa Bay defensive touchdown, not an offensive touchdown?
From the NFL Rulebook:
Rule 3, Section 35, Article 1 Whenever a team is in possession, it is the Offense and, at such time, its opponent is the Defense.
Rule 3, Section 35, Article 2 The team that puts the ball in play is Team A, and its oponent is Team B. For brevity, a player on Team A is referred to as A1 and his teammate as A2, A3, etc. Opponents are B1, B2, etc.
Note: A team becomes Team A when it has been designated to put ball in play, and it remains Team A until a down ends, even though there might be one or more changes of possession during the down. This is in contrast with the terms Offense and Defense. Team A is the offense when the down starts, but becomes the defense if and when B secures possession during the down, and vice versa for each change of possession.
However, clearly it's the intention in fantasy football to award things like interceptions and fumbles returned for a touchdown to the defensive team (because they are actually on the field at the time of the play), and not the offensive team. If fantasy football followed the letter of the NFL rules, there would be no such thing as a defensive touchdown, as all interception and fumble recovery touchdowns are scored by the the team with possession (i.e., the offensive team, if you follow the letter of the NFL rulebook).