It is hard to tell from the info provided and pics supplied what the beam's role is in regards to what it is supporting and what it is supported by and if it is a permenant fixture. Arc/Mephis have indicated it is supporting a ridge board which i would find it hard to believe, it appears you have roof trusses so why would you need something to support a ridge board? The roof truss design anyway you obviously use a steel beam in places where timber wont span the distance given the load it is required to carry.
So you need to understand (by some use of common sense and gravity) if it is a live or dead load or even point load that this beam is being used for otherwise it could have been used for temporary use only? (which it doesnt look like it is comming down soon) the use of more than one brick suggests they are merely packing the beam to the correct height until the rest of work is finished. either way if there is some load that could cause it to shift (laterally or by other means others have suggested) then at some point in time it would have to be tied down to resist uplift forces in your wind category in Perth.
The tie down method is what you should be looking in to as its is not that simple to join steel and wood. and sitting on 4 bricks suggests that the tie down method is going to be messy.