Google Summer of Code (and most likely other similar programs) build on
leverage: few Google employees manage a number of mentoring organization
who in turn manage a large number of students that Google could never
manage within the given staffing limits.

Mentoring organizations differ in size and scope. One type of mentoring
organization is particularly interesting for Google: Umbrella organizations
that manage a number of projects, such as Gnome or KDE. These umbrella
organizations provide added value with a layer of management and quality
assurance that would otherwise be left to Google employees screening
individual projects for mentoring organizations.

It is in the interest of the program to cater to such large umbrella
organizations.

With this request I would like to ask whether provisions have been made for
multi-level organization management; and if not whether it would be
possible or interesting to make them.

The first and most important request in this context would be to let the
admin segment the umbrella organization in many sub-groups that are treated
as separate entities for the org-internal slot allocation process (but
still as a single entity for Google's administration).

Once Google assigns slots to the umbrella org, the admin could create
sub-groups in the org, and allocate individual slots to each such subgroup
up to the number of slots allocated by Google. The admin would also
allocate student projects to these subgroup. This way, ranking would
effectively be separated into the subgroups without too much overhead (i.e.
mentors and admin would still be part of the same org and could just filter
proposals per subgroup).