1) When creating the tree with Sapling, choose 'Rectanglular' for the leaves' shape because it will allow you to create a UV map. Also, make sure to select the appropriate leaves distribution.
2) Select your leaves and enter Edit mode.
3) Open an Image/UV Editor window and Activate the "keep UV and Edit mode in sync" option in the UV editor window
4) In the 3D View, select 2 vertices that are on the branch side, they will appear orange in the UV Editor.
5) In UV Window, with the box selection, select all those "branch vertices" which are actually above each other.
7) Subdivide once, you get the vertices that are directly on the branches, select them as well in UV Window and separate with P in the 3D View.
8) A new object is created with only vertices, put a particle system on it with emission per verts. Done :)
Really useful to replace default leaves with nice 3D leaves as well :)
An example. I made the new leaves and fruit using that method (The branches are the default one, ugly but it's not the point) :