What's that, four USB ports on the new Model B+? That's right! The new Pi has even more USB ports. The original B had a 2-port hub + Ethernet controller, the LAN9512, which basically turned the 1 USB port on the processor into 2 ports + Ethernet.
The new B+ upgrades the LAN9512 to the LAN9514 - a 4-port USB Hub w/Ethernet. This replacement makes it possible to plug in mouse, keyboard, USB WiFi and maybe even something else all at once.
Don't forget! You need a new Kernel/Firmware
If you have an older Raspbian or NooBs or whatever (before ~ June 20 2014) do a sudo apt-get update and sudo apt-get upgrade to update your kernel & firmware! Without new kernel/firmware, the USB/Ethernet chip doesn't work so make sure you do this on a Model B since you need to have ethernet or USB to work in order to download it, eh?
