Quick question regarding indexes and NULLs in 7.3.3 -> 7.4

Folks,

I'm updating Joy of Index, and I wanted to clear something up.  In 7.3.3, and 
in 7.4 CVS, will IS NOT NULL queries use a regular index if NULLs are 
sufficiently uncommon, or does this still require an IS NULL partial index as 
it did in 7.2.x?   I don't want to mislead readers ....

-- 
Josh Berkus
Aglio Database Solutions
San Francisco