Fortune Cards. In 2nd ed, we used a 1d20 roll for that.
It would seem that 4e is wandering down the path of AD&D 2nd edition looking for loose rules to make a buck on. What possessed them to look at the Player's Option series is beyond me, but I'm rather boggled by the success of 4e anyway. Anyway, in Player's Option: Combat & Tactics, on page 18 TSR published a Critical Event Table. It was a roll made by the DM to determine a fog of war event, such as a N/PC falling over, collateral damage, or even the movement of all participants in a direction. I imagine this is more or less what fortune cards are, though I suspect that fortune cards are more geared towards helping out the PCs(further following their rule of cool philosophy which I don't really like in my own games). At the very least, these new cards might give some extra ideas on how to expand the Critical Events Table.