Eventually, we think most developers will create a gifts functionality that lies somewhere in between the “spam everybody” and “gift to a single friend” philosophies. One way for games like Café World to begin this transition would to change the default from sending to all your friends to just the users playing the game. Then take it one step further, allowing users to filter it to go to only their “active” Café World friends (say those that have played in the last week and thus are more likely to find value in the gift messaging).
Inside Social Games explores the gifting mechanics in relation to Facebook policies. Recommended reading for anyone interested in the virality of apps - that should be everyone, right?