dpreview TOP 15 Posters curently use, or more specific they *talk about* ( and this is a ranking of brands ):
1. Oly
2. Sony ( approx as much Sony users as Oly users, but a slight difference ),
3. Fuji
4. Nikon
4. Canon ( same # as Nikon )
6. Pentax
7. Panasonic.

I know the statistic is very small, perhaps someone else can repeat it with bigger statistic or average over several weeks and posting pages, The numbers after the nicknames are the total posts according dpreview posting statistic 7 days.
I just look where the TOP 15 posters in the statistics posted ( last page of posts ):

Oly = 4.5:
1 \*: Olympus Talk Forum: Digirame with his 159 posts ( surely not all 159 posts in that forum, but the last page )
3 \*: Olympus SLR Talk Forum: Bootstrap 141, Rriley 116, RoelHendrickx
101
0.5 \*: Micro Four Thirds Talk: Brian Mosley 125

Sony = 4:
Sony SLR Talk Forum: gpr2020 143, Barry Fitzgerald 128, Lens_Alchemy 121, zackiedawg 103

Fuji=2:
Fuji Talk: Kim Letkeman 102, AdamT 107

Nikon = 1.5:
1 \*: Nikon D300 - D100: olyflyer 107
0.5 \*: Canon+Nikon: brightcolours 114

Canon = 1.5:
1 \*: Canon EOS 7D / 50D: bronxbombers 96
0.5 \*: Canon+Nikon: brightcolours 114

Pentax=1:
Pentax SLR Talk: ozdean 106

Panasonic = 0.5 because MFT = Oly+Panny:
0.5 \*: Micro Four Thirds Talk: Brian Mosley 125

Mr. NoFlash :)