Now after we have root for 2.1 most of you will want to have app2sd also. The script posted in x10 mini pro android development forum (http://forum.xda-developers.com/showthread.php?t=804574
) works ok but it has one limitation. It moves only the /data/app folder to your ext2 partition on the SD card. The /data/dalvik-cache folder remains in the internal memory and this is why you still see your internal memory free space decreasing when installing applications.
I have modified the script so it also moves the dalvik cache to your SD card. I recommend to use at least class 4 SD card for this. I have attached the modified script. Follow the instructions from the original thread but use the files from my attachment. For me it works fine.If you have any problems please share so we can try to fix them together.
And finally using both the original and modified app2sd you CAN normally use your sd card as mass storage device.