Getting lm-sensors to detect fan speed, etc

[csj <csj@mindgate.net>]

I have built the lm-sensors modules and what-not, and run sensors-detect
and modprobe'd, etc. When I run sensors, however, all I get is:

:~> sensors 
eeprom-i2c-0-50
Adapter: bt848 #0
Algorithm: Bit-shift algorithm

eeprom-i2c-1-50
Adapter: SMBus Via Pro adapter at 5000
Algorithm: Non-I2C SMBus adapter
Memory type:            SDRAM DIMM SPD
SDRAM Size (MB):        256

Well and good. But it's telling me nothing I don't know already. How do
I get lm-sensors to detect the stuff I don't know, like fan speed and
system temperature?