Android - Is possible to make symbolic links in the android filesystem? (and how?)

Android does support symbolic links, but certain file systems (e.g. FAT or RFS) do not and you cannot create symbolic links in those partitions. If your device uses a filesystem that supports symbolic links (e.g. ext2, ext3, ext4, yaffs2) then you should be able to use ln -s from the Terminal Emulator.

I think this question on superuser answers your question, i.e. that the FAT filesystem on the SD card does not support symlinks.

Just to clarify (and as reflected in the SU question/answers I linked): the Android OS supports symlinks, but the FAT filesystem on the SD card does not.

It is possible to do this via the mount -o bind /old/dir /new/dir command as discussed here

You need root I guess.