Most of it can, but I am not sure if MicroBlaze kit can be downloaded as well.
As far as I know they offer the commercial version for several hundred bucks ( up to $20k for some versions ).
I really haven't tried to get it, but you can always try.
You can get many free designs from the internet along with their respective sources and development tools, so MicroBlaze is not a must for the beginner.
It is far too complicated to learn from, though it ihas many tools like C compilers, assemblers, and so on.
Actually the MicroBlaze is somewhat similar to the MIPS processor which is available from Opencores. The soft peripheral devices are compatible with the PowerPC bus structure. Take a look here **broken link removed** to find more about PB and MBlaze.
I suggest to explore some simpler cores like the PicoBlaze or '51 likes for the beginning. Those are easily obtainable almost everywhere, and there is abundance of tools for them too.
Regards, yego