The MicroSD card in my G1 has three partitions on it - a 3GB+ FAT32 partition for files, an EXT3 (maybe 4?) partition that my rooted phone puts the applications on, and a Linux swap partition.

I just bought an 8GB card to replace my 4GB card, and I want to try to make this as seamless as possible. Is there a way to image the entire card, with all partitions, put it on the new card, and then expand the FAT32 partition to fill? I can do the last part, but it's the first part I'm not sure of.

Do you have a computer that can read the SD cards? If so, boot into Linux (any live/repair CD should do), create your partitions on the new card to match your old card's partitions, except make the FAT32 partition 4GB bigger (fdisk is a Linux partition tool that should be available everywhere, otherwise parted), then just copy the old ext3 partition to the new one (cp /dev/sdc2 /dev/sdd2 or similar). The swap partition shouldn't need to be copied.

Hm, that would actually require that you have two card readers. You might need to figure out some intermediate space.

In summary, yes.

Are you sure you can make a 7GB FAT32 filesystem?

FAT32 should go up to 2TB, with a max filesize of 4GB.

http://en.wikipedia.org/wiki/File_Allocation_Table

Parted Magic should do what you need. You will just need two MicroSD card readers.

When I setup my 16GB microSD card for my G1 all the instructions say to make the fat32 partition first. If this was done to your card expanding the Fat32 partition might not be an option using imaging tools.

I would setup your new card using Parted Magic then connect the card currently in your G1 and just copy everything over 1 partition at a time.

Wow, I'm amazed that they can get away with calling their application Parted Magic. I guess since they're not selling it...