Sort of. In the traditional sense the NB handles RAM and GPU traffic. The SB handles SATA/IDE ports, audio, lan, etc. All the onboard devices usually go to the SB, then to the NB, then finally the CPU. If the GPU is on a PCIe bus, then the "PCIe" is handled by the NB.
Things changed a bit when AMD/IBM put the memory controller on the CPU. The CPU could directly get info from the RAM without needing the NB. At this point the NB started to only handle GPU duties. Intel then put that on the CPU as well, so the NB is pretty much gone. The rest of the PCIe slots usually talk to the SB. (there are some odd boards that have PCIe 16x slots that go to the SB, or to another chip. (NF200) These aren't very common but they do exist.)
Why are you asking if you can look up the info on wiki? And seeing as your there, what is the Back Side Bus?