Dear AJ,
This function is on our TODO list and it may be included in igraph 0.6.
The current stable version contains no such function at the moment. If
you wish, you can track the progress of this feature in the
corresponding bug report:
https://bugs.launchpad.net/igraph/+bug/372740
Currently what you can do is to find all shortest paths from a single
node to all others (see get.all.shortest.paths in the documentation).
This is overkill if you need all the shortest paths between vertices V1
and V2 only, but if your network is small, then this might work.
Also, please consider subscribing to the igraph-help mailing list
(address@hidden) if you are asking questions. Someone else on
the mailing list might be faster in replying to a question than me :)