Aggregate "rollup"

I had written a piece of code about two years ago that used the
aggregate feature of PostgreSQL to create an array of integers from an
aggregate, as:

select int_array_aggregate( column ) from table group by column

While it seems pointless to create an array on a select, it has a
purpose in OLAP. For instance, suppose you do this:

create table fast_lookup as select reference,
int_array_aggregate(result) from table group by result

The "fast_lookup" table now has all the result entries as an array in a
single row. In the systems that I have used this, it has provided a
dramatic improvement, especially when you have a high number of
identical "reference" entries in a classic "one to many" table.

The question is, would a more comprehensive solution be wanted?
Possible? Something like:

create table fast_lookup as select reference, aggregate_array( field )
from table group by field

Where the function aggregate_array takes any number of data types.

Any thoughts? I think I need to fix the code in the current
/contrib/intagg anyway, so is it worth doing the extra work to included
multiple data types?