When connecting a USB cable to the SE K610i, it can be switched to USB/MemoryStick reader mode, in order to be able to access the music/MP3s for instance.
There's a way to have it recognised automatically as a portable music player, easing its integration with tools like banshee or rhythmbox, provided the correct HAL FDI files are there.
As mine was incomplete, I proposed the following patch to HAL maintainers.
Hope this helps.
An other way to access its files (OBEX over USB) was described previously in another post.