8.3 Question (Updateable cursors)

Trying to plan and get a bit of a jump on 8.3

I see an original project description for Updateable cursors at:
http://archives.postgresql.org/pgsql-hackers/2007-01/msg01014.php

I'm wondering if there is an updated description somewhere on the site - or better still -- some advice as to whether the PG implementation will  pose the same potential penalties as described for Microsoft SQL Server as described at:
http://en.wikipedia.org/wiki/Cursor_%28databases%29
towards the bottom of the page (Disadvantages of Cursors).

Thanks