WireShark doesn't decode gzip'ed http traffic on Windows

If you look at the protocol tree under the "Line-based text data" entry you will see the uncompressed data. The "Follow TCP Stream" dialog just shows the contents of the TCP payload and doesn't interpret it as HTTP or gzipped data or anything else. The buttons on the dialog allow you to set the display format for the stream bytes.

You can right-click on the uncompressed data(see the red # below) and select 'Export Selected Packet Bytes...' to save to a file

The accepted answer is the correct answer in terms of current Wireshark -- but is pretty clumsy to use IMO.

So I wrote a small script wireshark-http-gunzip (requires Ruby) to convert the whole output to a format you'd expect. Hope anyone that stumbles here find it useful.

There is support within Wireshark now. Just right click on top of a packet identified as HTTP (Protocol column = HTTP), then "Follow" and "HTTP Stream". This should decode compressed responses into plain text.