Postgres 9.1 wait events
There isn't such a fine grained tracking available in Postgres (other than using DTrace which apparently gives a lot of information).

There is a whole chapter in the manual "Monitoring Database Activity"
http://www.postgresql.org/docs/current/static/monitoring.html

Another option is the module pg_stats_statements:
http://www.postgresql.org/docs/current/static/pgstatstatements.html