We have added File transfer support to our client for GoogleTalk. It allows you to select any number of files (even folders and files together) to be transferred to and from the PC. We are using a direct P2P connection (without any hosts in between), and that allows for very fast connections. If you are on Wi-Fi, transfer speeds can be even faster than transferring via ActiveSync.
This is probably the most advanced network file transfer on the Pocket PC out there.
Also, I saw a post by Menneisyys (and his blog) about IM messengers -- just to clarify -- our client connects directly to GoogleTalk servers using XMPP (Jabber) -- it doesn't connect to our servers directly. The AIM/MSN/Y!/ICQ are implemented using Jabber transports, and they connect through our server.
There is also a bug in GoogleTalk servers where users of the type "msn1.octro.net " (ones without userid@) couldn't be added properly, and thus cause a request to GoogleTalk every time. We have removed the need for this in our transports (changing our transport to
msn@msn1.octro.net). This has caused older versions of OctroTalk to stop working with legacy accounts. If you are using Legacy accounts, it can be used only with 1.12/1.09 or later.
Enjoy!