Well, the first thing that popped into my head was to put something in there to act as a pedestal and put a pot of asparagus fern in there....that gets really bushy and big and would hide most of the pipe. You could put some bling into the pot to dress the area up too.

You wouldn't want to just cut the pipes off. The furnace emits Carbon a monoxide. You need to make sure it is properly vented.

Painting it to match the siding would be a huge improvement. Our furnace vents onto our patio. There isn't much I can do to hide it so I painted to match the siding. Huge improvement,

I agree with Marlene about the bushy plant. You could use a two step ladder to put over it and then put plants and junk on that. I have also hidden an eyesore with a small picket fence that can be decorated. Good luck and show us a pic with what you come up with!

A Lattice Shelf over it. With potted fern or something you would never know it's there.

My serious concern is that the pipe is facing upward. Show this to your landlord because when it rains the water is running directly into ..well I guess your furnace if this is what this vent pipe is for.

I agree with citytransplant. Number one concern is the vent opening is facing skyward and not toward the ground. Past that, pixie_Lou suggested painting it to match siding. I do this to all my vents, water lines, etc. Works great, the eye does pick it up as quick. Others have very good ideas too. My input, I need to know your zone and amount of light it receives (which way the wall is facing.) depending on your zone, there is a vast number of bushes (flowering and inexpensive) you could use also.

I think Pixie is right. The tee at the end makes the vent draw air to exhaust carbon monoxide. Leave it alone. I'm pretty sure CO will kill any plants nearby.
Don