Can I take Photoshop map into Illustrator so it is scaleable Vector drawing?

[Gamerprinter]

That is unfortunate, really. As I said I haven't tinkered in Illustrator at all, but for all the benefits of vector scalability, it isn't the strongest tool to make the maps in.

I disagree. I am a professional fantasy cartographer having done many commissions for RPG publishers and for my own RPG publishing projects. Although I sometimes incorporate hand-drawn linework that is digitally scanned and imported to my preferred vector application - Xara Designer Pro 9, almost all my maps are entirely created in vector. I never use image editors such as Photoshop or GIMP anywhere in the process of creating high end, professional maps. Arguably some of my maps look like they are entirely or partially created in image editors, and that is not true at all, in my case.

Can you, though, take the skeleton of the map, say the initial line drawing, convert that to the vector scalable file illustrator offers and then take it back into Photoshop to add detail on the scaled map? Or am I further ahead to just go nuts with pixel/inch on my world map so I can crop portions for regional maps that are still usable?

You can always work in multiple applications, including both image editors and vector apps, many cartographers do just that. There are features in vector for instance like creating tapered lines for diminishing rivers or detailed label work, that though can be accomplished in image editors is faster and more easily accomplished in vector. Many cartographers do their labeling, borders and other detailing exclusively in vector, even though the rest of the entire map was created in an image editor. Despite that you are still at the mercy of working in whatever scale and pixel resolution you began with at the start of doing your map in Photoshop or GIMP.

When I do import hand-drawn linework to vector, I see no obvious need to vectorize it. Rather I keep it in its raster format, apply transparencies and other filters in vector to make it usable as a major element of my map. All my maps include composites of vector and raster objects, while completely created in vector. Why do I need to vectorize the linework, it looks just as good in raster, and as long as the white areas of b/w linework is fully transparent. I don't need the linework to be a vectorized object. When vectorizing you often get unneeded artifacts that are failures in the vectorization process. Its better to keep the raster as raster, though to your original argument raster scales poorly.

Although I use both image editors and vector in my daytime graphics job, I still prefer and appreciate the powers of vector over anything I might do in an image editor. For me, if I need to adjust the color fidelity or midtones versus contrast, I would do this using curves in Photoshop. So I only use image editors to tweak the color or apply specific graphics filters. I don't actually use it to paint in the detail, that kind of work I do exclusively in vector. I can achieve a very painterly look even only using vector. So for my production process, I see no advantage in using an image editor, and thus never do so.