If I understand what you mean, I'm having a similar problem. I went to the iTunes store on my iPod touch, and was upset when I found out I can't search for podcasts in the store and download them, or even find them at all...
I don't know if your touch is different from mine but "Audiobooks" is one of the standard options under "Music"
Touch the "Music" icon. At the bottom of the screen that comes up you'll see five areas, the last one on the right being "More". Touch "More" and another screen comes up with five more choices, one of them being "Audiobooks".
Touching Edit on this screen brings up a screen where you can customize the location of the various Music screen icons. Just touch whichever one you want and move it to the bottom to replace one of the others.
If I understand what you mean, I'm having a similar problem. I went to the iTunes store on my iPod touch, and was upset when I found out I can't search for podcasts in the store and download them, or even find them at all...