This might be asking a lot, but is it possible to determine the boundary for a particular territory?

For example, there are 4 postal codes making up a single territory - is there any way to know the vertices of the outer boundary to create a freeform shape that matches the outer boundary?

I think this is impossible short of reading and interpreting the bitmap (raster to vector conversion) which would not be trivial.

There's a past article about determing the starting point of a route which takes off in this direction if you really want to do it

You should consider purchasing the zip code boundaries you require from a GIS data vendor, preferably the same source that MS is using for MapPoint zip code boundaries (GDT?).

Eric

I have a feeling that even with the GIS boundary files, it would be tough to get only the "outer boundary" of the territory and not showing the boundaries of each individual postal code within the territory.

You are right there.. it would depend on the data as well as getting some software tool or routine to merge the boundaries. It is a pretty standard feature of GIS software to merge territories, but to work good the data has to line up properly or it might leave slivers between zip codes. One good thing about GDT, although they might charge a premium price, their zip code boundaries should be good and not have this problem.

Eric