Music player usage is a power law just like everything else.
At least if you believe these figures from Audioscrobbler:
The good news for me is that iScrobbler for Windows is the second most popular plugin even if it lags seriously behind Winamp.
lastscrobplugin | count
-----------------+--------
wa2 | 17667
itw | 5518
wmp | 2920
osx | 1846
foo | 1823
xms | 591
ark | 533
qcd | 205
jmc | 74
rbx | 39
slm | 27
tst | 9
shk | 4
mdn | 3
bmp | 3
mpd | 2
noa | 2
pte | 1
123 | 1
The good news for me is that iScrobbler for Windows is the second most popular plugin even if it lags seriously behind Winamp.