Yes i know many other baking options in the new 2.43 release from here
and read here that the Tanget baking will be added…
http://www.blender.org/cms/Render_Baking.827.0.html
and i just would like to know that in 2.43 or later release will be added? 
i think tangent space normalmap more usable than object space normalmap.
Actually, it’s not object space but world space… which is completely useless.
Ton’s just been too busy to actually code tangent space. I doubt it will be in the next official release. Actually I’m sure it won’t be.
Does this mean this type of tangent space is world tangent not object tangent?
No, it means that the normal map created by the new internal Bake function is created in world space in stead of tangent space. Which makes the Baked map useless. You can use tangent space normal maps perfectly, just not generate them yet. But I’m sure that it’ll be in the next release (after 2.43).
i think it is the same as math, it uses the tangent vectors to trace a normal map, i could be wrong though.
after 2.43? its means we can waiting for this about 6 months? 
any other solution baking tangent space normalmap within blender?
Falgor:
i dont know exatly what mean tangent but i think it is relatively form polygon surfaces so it think this methods store the micro polygon data relatively form poly surfaces in pixles -picture.
If u try the polygon paint tool in sculpt mode i.e. the very high level 10 where
the polygon extra high u can baking the tangent space this level and applying to lower poly level but the looks of the mesh will same.
Tangent space normal map as I understand it.
Say you are rendering a surface, now normally the shadows/specularity and everything is calculated relative to the angle of the surface and where the lamps are relative to it.
Now if we have a tangent space nomal map, The colours in this map define how the angle of the surface will be changed for each point. So say the angle of the surface would be zero degrees normally, perhaps a green dot in the map would virtually turn it 30 degrees in x direction. So the light on that point of your mesh is rendered in a different way than it would be if it was just a flat surface.
As macouno told, normal maps store data, in which direction the light has to be reflected from the surface. Each pixel in the generated map represent a vector (R,G,B values tell a direction, their value is normalized, meaning that the lenght of the vector is exactly 1). As vectors need a coordinate system in which they can be described, you have to tell which system they are relative to. Talking about world space means, that the RGB values are simply told according to the base coordinate system (the base XYZ axis). Object space is similar. This system might have transformations (translation, rotation) in world space.
World space normal maps can be used for non-moving, non deforming bodies.
Object space nmaps are good for movable, rigid (non deforming) objects. (transformations of the object don’t affect the lighting, as it is relative to the object space and not to the world space)
…and here we go: tangent space. Imagine that you design a coordinate system for each vertex. The nmap values are now calculated relative to these (NOT ONE like the other two mentioned above!) systems: every pixel has an interpolated system of the 3 affected coord-systems of it’s tri, values are stored according to that. Why is it good? Now you can deform the object, the nmap still can be used. For example a character might use it. It even means that the coordinate systems have to be stored per vertex. If you don’t have this data or you don’t know the exact algorithm to recalculate them the way, as the nmap generator, tangent space nmaps are useless or at least they give bad results.
I have try Nvidia Melody to generate tangent space normal maps from hipoly model to lowpoly model. Somebody use this program?
Try Xnormal, it works for me at least:
http://santy.xnormal.net/santyweb/Projects.aspx
Try This,
http://engineering.soclab.bth.se/tools/177.aspx
It’s called Open Render Bump (ORB).
Its an amazing program that can create Tangent based Normal maps, and Displacement maps. It even gives a real time preview.
somebody know a alternative Tangent baking solution on linux? (ubuntu)
Mettepiu:
I cant extract the tar.bz2 files. (source and binaries) maybe too old version.
I’m with squareline on this one. Is there some open source alternative for OS X as well? It really is too bad Blender cannot make tangent normal maps yet. But I wouldn’t be surprised if something popped up on blenderbuilds in the coming weeks. 
try to use the command line or to change tool, the source archive is working fine
here…
Ok, we need to wait tangent baking in Blender, but baking AO from hipoly to lowpoly is possible now?
endi:
yes possible.
I painted a high resolution multires model and than switch to the low poly level and assing a texture in uv editor and baking AO or world normalmap.
here is the result: