My
Sony Ericsson W910i works as a USB Mass Storage device. When you plug the USB cable in and connect the phone, you have to select "Mass storage" mode on the phone for it to show up as a normal drive (there is the option on the screen to do this), which can be mounted like any other disk (/dev/sda1 or whatever).
There's no generic software for transferring media to phones because they all use proprietary protocols to connect to the PC. Getting them working under Windows requires the installation of numerous drivers, none (or very few) of which have been reverse engineered to work in Linux.
Fortunately, my phone came with a M2 USB adaptor, thus anything I want to transfer can be moved to the card as though it were a memory stick.