what does it mean when they talk about the number of "channels" a bus has? for example they'll say that some board or something has a 2 channel i2c bus or ide bus. what are the channels and what does it mean to have more of them?

The bus is the circut which makes it possible for ur computer to exchange data between all your hardware devices. It is like a highway as more lines as you have as quicker the transfer of data can be.

Here a link if you want to read more...

http://en.wikipedia.org/wiki/Computer_bus

so, the number of channels is the number of wires/lines that the bus can send data over? i guess the data is sent in parallel so the more channels the faster it goes? what about serial devices like sata? do they only have 1 channel?

If you have a look at the two links on the bottom you should see does I2C is a bus technology for pheripherals and other small stuff like controlling/ turning on and off devices (like sound,lcd, receive temprature impacts) and many devices are listed for usb connection usage. They also mention does I2C is a subset of SMB which means System management Bus, while IDE is a technology standard used to connect drives to the system for example, cd rom harddrivers ect.
I couldnt find if there is a restriction for channels. Althoug i know there is no limitation generally to the amount of channels you will have.
Basically every bus has channels and MHZ and this defines how quick data can be sent trough.

i hope this comes closer to your question, maybe read the wikis on the bottom which helps you to understand the technology and have a look if in the standardizing papers the amount of channels are described!


http://en.wikipedia.org/wiki/I2c

http://en.wikipedia.org/wiki/AT_Attachment

http://en.wikipedia.org/wiki/SMBus