When Studs Terkel's book about it, _The Good War_, came out, the
generally accepted death toll of US soldiers in WWII was about a
quarter million.  More recently, a quick glance at the Encyclopaedia
Britannica edition of 2000 gives a figure of 292,000 soldiers and 6000
civilians for a round total of about three hundred thousand.  In the
recent Memorial Day speechifying, however, everyone from the President
on down seemed to be bandying about a figure of 400,000 US deaths in
WWII.

What's going on?  Where are all these new WWII casualties coming from?
 At this rate WWII is killing Americans faster than al Qaeda.

It is quite normal that they count war related injuries which are
related to the cause of death into the finial count of casualties.  As
the survivors grow older from WWII then many become more susceptible
to complications from their War injuries. In all due respect to them ,
they are included in new counts- which explains the raise in numbers.
I would imagine that other countries also raise the death toll in the
same manner.

Thanks for your comment.  Several people have suggested variations on
that idea to me.  Three problems with it occur to me:

1) Who identifies (and how) the belated-deaths-due?to-war-injuries? 
For instance, I have never seen a octogenarian's death certificate on
which the doctor wrote, "Death due to complications from injuries
suffered sixty years ago".

2) Even if there is someone making and tracking these kinds of
determinations, if a former soldier lives a pretty normal lifespan,
calling his death at 80 a "casualty" from a war that happened 60 years
ago pretty much makes a mockery of the entire concept of war
casualties.  So if this really is the reason of the rising casualty
numbers, it means that the figure has become essentially meaningless. 
I expect almost everyone involved in any war experiences some kind of
adversity, so eventually the casualty toll will be 100% when all the
veterans pass away no matter what the cause.

3) Though there have been odd cases of a name here or there being
added to the Korean and Vietnam War casualty rolls, these are isolated
cases, undertaken only after significant forensic investigation.  For
WWII, there was a wholesale increase in the casualty count of 100,000
souls between 2000 and 2004. There is nothing in any other US war to
match this kind of re-assessment.

I'm not sure, but the most likely answer is that soldiers that were
MIA (Missing in Action) are being discovered as KIA (Killed in
Action).  The US Military is constantly examining remains found in old
battlefields.  Most research is being done in Vietnam of course.

By how much are these numbers changing?  I never that close of attention to notice.

I just read your post again.

I wouldn't trust estimated numbers.

There aren't any new numbers.

Encyclopedia Britannica is using battle deaths, 291,557, according to
the DOD (ref http://web1.whs.osd.mil/mmid/casualty/WCPRINCIPAL.pdf )

The total number of deaths, including non-battle deaths of over
100,000, bring the number to 405,399 according to the DOD, which
matches what you heard in the Memorial Day speeches.

When I read about Civil War battles when I was younger, I was confused
about the different numbers thrown about.  This is when I found out
that the term "casualty" doesn't refer to just deaths, it also
includes wounded.  Thus, if you were actually talking about WWII US
military casualties, the number would be over 1.1 million, adding in
the over 671,000 non fatal wounds from the DOD information.