Successful pocket neighborhoods start with the central idea of a limited number of dwellings gathered around a shared commons.  When the number gets larger than 8 or 12, other clusters form around separate shared commons, connected by walkways.  Multiple clusters can form a larger aggregate community.  These communities are not isolated to themselves, like a gated community, but connect and contribute to the character and life of the surrounding neighborhood.  It is essential that cars and traffic do not invade the shared pedestrian space.  The active rooms of the homes, including front porches, face the commons rather than turning their back to neighbors. As noted above, there is a layering of public to private space, and careful placement of windows to ensure privacy for each dwelling.  These are core design principles, essentially.  Read the book for further principles, far more articulation, and examples. 

In many pocket neighborhoods, residents park their cars away from their homes, having them walk through the shared common area on the way to their front doors.  Is this viable in cold climates? 

This relationship between the car door and front door greatly increases the level of interaction among neighbors and strengthens their bonds.  For many people, the short walk is not considered a hardship, even in snowy or rainy climates.  That said, others feel that having an attached garage is an amenity or requirement that outweighs the community-building benefits of the walk through the commons.  It’s still a pocket neighborhood, but with fewer chances to meet.