The following bug has been logged online:
Bug reference:      5850
Logged by:          Joshua Farray
Email address:      farray@gmail.com
PostgreSQL version: 9.0.2
Operating system:   Win7 x64
Description:        UPDATE statement fails when using aliases
Details:
Make a table:
> CREATE TABLE foos
> (
>   foo_id serial,
>   foo_text varchar(255)
> );
Update the table using an alias:
> UPDATE foos AS t
> SET t.foo_text = '';
Expected output:
> UPDATE 0
Actual output:
> ERROR:  column "t" of relation "foos" does not exist
> LINE 2: SET t.foo_text = '';
>             ^