Update blocking a select count(*)?

Hi all,

I am using postgresql 9.0 and I am updating a large table and running a
select count(*). The update is run first and then the select. The update is
blocking the select statement. To use the term MVCC (as seems to be done so
much in this list), well it seems to be broken. MVCC should allow a select
on the same table as an update, in fact nothing at all should block a
select. Also for some reason, the update query seems to always get an
Exclusive Lock which doesn't make any sense to me. At most an update should
require a row lock. This seems to also apply to two updates on the same
table in parallel.

Do I seem to have this right and is there anything I can do?

Thanks,
~Ben