I don't know if this is still news but I found this P1i iSync plug-in on the Sony Ericsson website. I was looking for an opportunity to sync my Sony Ericsson P1i via iSync for donkies and I'm pretty sure SE did not have one. Several forums reported that they removed a first version due to several issues with calendar syncronization. But now it seems they fixed it and posted it again. So I installed it and all I can say is that it works fine (so far).
Click here to download the plugin.
Update (July 20th 2008): It seems Sony Ericsson took down the plug-in again. I can't see the reason, it still works fine for me. However, according to several forums there have been some issues with syncronization from the mobile towards the Mac. So maybe the SE guys are still trying to fix that.
Update (Sep 21st 2008): Seems the plug-in is back on the SE site.