Create Index Locking Question

I need to create a new index on an existing table. The table is constantly
inserted into every second. Does CREATE INDEX require an exclusive write
lock on the table? If it does have a write lock what happens to the insert
statements at the time, are they simply played later or do they fail?

From http://www.postgresql.org/docs/8.1/interactive/sql-reindex.html I see
CREATE INDEX apparently requires a write lock, but I'm not 100% certain
because the CREATE INDEX was used to describe part of the REINDEX command.

The CREATE INDEX page makes no mention of locking issues:
http://www.postgresql.org/docs/8.1/interactive/sql-createindex.html

Could someone please clarify for me: Will I lose the INSERT statements
performed while a CREATE INDEX is running?

Regards,

Mike C.