array question

Is there any easy way to get this data:

kls_dev=# select * from ary_values;
agent_name | myval
------------+-------
a | 1
a | 2
a | 3
b | 4
b | 5
b | 6
(6 rows)

to look like this:

kls_dev=# select * from ary_test;
agent_name | vals
------------+---------
a | {1,2,3}
b | {4,5,6}
(2 rows)

In other words, I would like to group by 'agent_name' and then convert
all the 'myvals' associated w/ that agent_name into an array.

I tried a few simple things like this:
kls_dev=# select array_append(myval) from ary_values group by agent_name;

but no luck so far.

Thanks,
Whit