full join...using and version of pgsql

hello list,

i am using pgsql 7.2.1
i need something like

select * from t1 full join t2 using(bla) full join t3 using(bla)

i searched the archives and found that this is not possible with my 
version of postgres.
is this implemented in newer versions of postgres? since which version?

i'll try the alternative select * from t1 full join t2 on(t1.bla=t2.bla) 
full join t3 on(t1/t2.bla=t3.bla)
but this is not the best solution for me i think....

regards
tina