Long story short, after messing around trying to figure out why my phone would sometimes connect to my computer and sometimes not, I discovered the USB cable that came with the phone was no good. (for data transfer anyway, it always charged the phone) I Google'd this and found a thread from another forum with the same thing. It might not be that wide spread of a problem, but just something to look into if your are having a bit of trouble getting your phone to connect to your computer.
Samsung Momento USB Connection on Gentoo
Samsung Momento USB Connection on Gentoo