Out of memory errors on OS X

I have a couple users trying to install Postgres on OS X. To the best
of my knowledge, both of them are using 7.4.5/10.3.5, and got identical
errors while trying to init the database:

Reducing the shared buffers didn't help.

Any thoughts would be appreciated.

Jeffrey Melloy
jmelloy(at)visualdistortion(dot)org

William-Rowcliffes-Computer:/Users/wmrowcliffe postgres$
/usr/local/bin/initdb -D /usr/local/pgsql/data
The files belonging to this database system will be owned by user
"postgres".
This user must also own the server process.

The database cluster will be initialized with locale C.

fixing permissions on existing directory /usr/local/pgsql/data... ok
creating directory /usr/local/pgsql/data/base... ok
creating directory /usr/local/pgsql/data/global... ok
creating directory /usr/local/pgsql/data/pg_xlog... ok
creating directory /usr/local/pgsql/data/pg_clog... ok
selecting default max_connections... 10
selecting default shared_buffers... 50
creating configuration files... ok
creating template1 database in /usr/local/pgsql/data/base/1... FATAL:
could not create shared memory segment: Cannot allocate memory
DETAIL: Failed system call was shmget(key=1, size=1081344, 03600).
HINT: This error usually means that PostgreSQL's request for a shared
memory segment exceeded available memory or swap space. To reduce the
request size (currently 1081344 bytes), reduce PostgreSQL's
shared_buffers parameter (currently 50) and/or its max_connections
parameter (currently 10).
The PostgreSQL documentation contains more information about
shared memory configuration.

initdb: failed