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According to the Official TF2 blog, there are new additions to the Source SDK that will make it easier for beginning map makers to make maps. One of the main additions is the ability to modify pre-existing maps instead of having to start with a blank slate. For example, one could change around where health and ammo packs are placed (along with what kind), or add more spots for Engineers to add sentries. Valve is planning on adding this feature to more maps in the future.