after some quite bothersome experieneces I am left with an o.k. working installation of Twonky Server for mac.
Out of two issues left, this is one:
Twonky Server (latest, downloaded a few days ago) will not transcode to my iPhone 3GS.
On the iPhone (iOS 4.1) i use PlugPlayer (v3.8.0, latest).
I can stream *.mov - files, even a HD one.
Other files, like a divx-encoded file, will only result in a Quicktime-symbol being displayed within PlugPlayer.
Interestingly, the running time is displayed correctly.
VOBs will result in a crash of PlugPlayer.
I have installed ffmpeg (0.75 I think) via macports and pointed Twonky server to it. I also tried the binary from http://go.to/osxffmpegcompiling
(0.83), doesnt help anything.
On the config-page, the files will briefly be displayed under "serving local files", only to stop a little bit after the symbol is displayed in the iPhone.
I tried to assign different profiles to the iphone, from PlugPlayer ti Apple iPhone, but didnt succeed there as well.