May i find out how about late 2008, 13-inch MBP battery replacement. Is it the same as the 15" and 17" ?

Welcome to the Apple Support Communities

I think you are referring to the Late 2008 Aluminum MacBook. It's an Unibody computer, and this MacBook has got a non-replaceable battery. You have to take the computer to an Apple Store or reseller to get your battery replaced.

The steps of the link you gave are for non-Unibody MacBooks Pro, that have got a replaceable battery. In this case, you have to buy the battery from the Apple Online Store

This may be what you are looking for:

http://store.apple.com/us/product/MB771LL/A/rechargeable-battery-13-inch-macbook -aluminum

Ciao.

It is not the same battery and is only used in this particular model. The Apple Store still has them and I have even seen them in physical stores are well.