uuids with btree_gist

I'm trying to use timestamp ranges to keep track of the values particular items had over time, but I'm unable to create a table as follows:

test=# create extension btree_gist;
CREATE EXTENSION
test=# create table v(item uuid, lifetime tstzrange, value text,
test(# exclude using gist (item with =, lifetime with &&));
ERROR: data type uuid has no default operator class for access method "gist"
HINT: You must specify an operator class for the index or define a default operator class for the data type.
test=#

It works fine if I make item a text field.

test=# create table v(item text, lifetime tstzrange, value text,
test(# exclude using gist (item with =, lifetime with &&));
CREATE TABLE
test=#

Is there any reason that the required uuid access method isn't implemented? How hard is it to implement this?

Thanks,

Martin