As i read, Piwik works through js tracking and a counter-pixel.
Is it technically not possible, or why is piwik not also using server Logs?
It simply wouldn’t provide most of the data and its a lot of work to make that work.
Thomas is right, many reports will be missing from importing apache logs, but this will be possible in the future, maybe a few months away: Piwik will be usable as the new AWstats 
ok.
I don’t know much about doing Statistics, how to access logs from php, log-formats etc.
I just thought it might be a good way to complement JS tracking, that the combination of both would be more than each separate.
eg. downloads should be at least registered easyli i think,
and maybe it could make the counter-pixel obsolete?
(Maybe only for domains where piwik runs on the domain to be tracked)