Does Rageblood Shaman give itself +1/+1?
The Shaman has what is called a Static Ability. These kinds of abilities are active as long as their source is on the battlefield. So it will be active from the moment the Shaman enters the battlefield until the moment it leaves.

As for what it effects, "Other Minotaurs" means exactly that, any Minotaur other than the one with the ability gets the +1/+1 and trample. If you happen to control 2 of the Shamans they will each effect the other one, but they will not effect themselves.

In order for an ability like that to grant itself that ability it needs to drop the "Other" and just say "Minotaur creatures you control get +1/+1 and have trample." An example of this template is almost any Sliver.

Also note that the Shaman already has trample, so the part of the ability that you should be caring about is the +1/+1.


  604.1. Static abilities do something all the time rather than being activated or triggered. They are written as statements, and they're simply true.