The new T-Mobile G1 uses SD Card to expand its memory. I found that Amazon is selling the G1 Accessory compatible with the T-Mobile G1. It includes the SD Adapter needed to read the SDHC card in the computer. It’s $21.48 for 8GB for the G1.
This is the best price I have found buying memory for my T-Mobile G1 Phone that hasn’t arrived yet. It is the Sandisk 8GB microSDHC memory. The default G1 Memory is only 1GB. You can add up to 8GB of G1 memory with a microSD Card. With the SD card at this price you could have many memory cards and do something that would nostagically remind the Sega Mega Drive.