For cards like microsd, SD, etc? What about the iPhone 3G 8GB? Is the 8GB built inside the phone? Or is it an sd card that I can take out? Please help! Thank you.

Unfortunately, no. The iPhone doesn't support any kind of expandable memory. They're thinking, "Who needs expandable storage when there's cloud computing and sending via e-mail. However, the 8gb memory it does come with (which isn't even a full 8gb; usually it's 6.62gb or something like that) is built inside the phone.

All iphones have built in memory none have sd cards