Built-in flash in P&S digital and DSLR cameras

The other day, I saw the new Sony P&S camera - DSC H3. On top of the
camera, it was indicated that it has a strong built in flash. I went
to search about built-in flash feature in a digital camera at the
dpreview website and found the following:
For P&S digital cameras: Canon G7 has a weak flash, Flash guide of 4m.
Canon S51S is stronger. Sony H3 has a Flash guide no. of 7m, while as
Sony DSC H7 or H9 is the strongest I found for P&S camera - Flash
Guide of 9.8m. Canon SX100 is even worse than the G7/G9 - at only 3m.
Lumix Fz18/FZ8 has a flash guide of 6m, and FZ50 has 7m. Nikon 5100 is
much better than G7/G9 at 8m.
For DSLR: Most cameras with built-in flash has Flash Guide around
11-13m. Canon 5D does not even have a built-in flash. Surprisingly,
Nikon D40 and D40x has flash guide no. of 17m. As comparison, Canon
40D/30D/Xti all have only a flash guide of 12m.
- Why P&S cameras have relatively weaker built-in flash than the DSLR?
Could P&S cameras be designed to have stronger built-in flash like a
DSLR?
- I noticed that my P&S camera usually is too weak to take picture in
large indoors (restaurant, meeting halls, etc). Could this be improved
by stronger flash? I have always complained in the past that most P&S
cameras have tiny built-in flash, and without a hot-shoe, you cannot
improve your lighting in indoor shots.
- Anyone tried the built-in flash in Sony H3 or Sony H7 and H9?. Are
they much better than flash in other cameras, particularly the low
ones like Canon G7/SX100? Does this mean that Sony H3/H7/H9 is
superior for taking photo indoors for people in a group than, say
Canon G7/G9?  I found that Sony H3 is a good competitor against Canon
G7/G9 or Nikon P5100. It may have less features than G7/G9, but it
makes good quality images and it is cheaper than a G7/G9. It is also
as compact as a G7/G9 or Nikon P5100.
- Is built in flash in Nikon D40x really stronger than flash in a
Canon Xti?
- How much difference are relatively between a Flash Guide of 3m, 7m,
12m and 17m ? I assume that this is all based on ASA100? Does a flash
guide 17m mean that you can get a good coverage of flash to 17m
distance?
- Panasonic Lumix L1 is about the only DSLR camera that has extended
pop-up flash feature (ie. 2 level heights). What is the advantage of
this? Less red-eye images?
- Are there digital cameras (P&S or DSLR) which have two or more modes
of flash strength in their built in flash?
Thanks for the info and discussion.