>> Good hint, Opera 7.10 does it, but not mozilla and IE :(
> Perhaps ethereal will be helpful here, you could use it to capture the
> http session and see it's content(See "Tools->Follow TCP Stream")

I captured the output already (thanks for hint) but I don't know how to 
verify the compressed data block. All other seems to be OK, a PHP setup 
delivered the same headers, only the compressed data differed...

thanks!
Dominik