Hi,
The use of SD card partition is to split the SD card storage. For example, if you have an 8GB card, it would be recognised as two 4GB cards.
There is no such option on the handset as standard to enable this however there would be a very limited benefit in doing this with a handset as it is only designed to recognised one SD card. If this was something you were interested in doing, I could only suggest checking through the Android Market for any apps which may provide this type of functionality.
