Wirelessly posted (Cingular 8100 Pearl: BlackBerry8100/4.2.0 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/102)
Don't bother trying to block SMS or MMS with the BlackBerry's firewall settings. Sure it'll block them just fine, but the charges will still apply.
I haven't been spammed, but I did miss several txt messages from my ordinary cellphone carryin' friends and was charged just the same.
Oh well. It's only a $1.20 a dozen.