Could 51% attack really happen?

[alexwolf011]

I have seen many words related to 51% attack but I never knew which coin does really suffer it.

If someone really starts 51% attack, he/she will need huge hashpower and is hard to make profit?

So, is anyone know which coin ever suffers 51% attack?

For now, there are so many coins having very low hashrate. They are really in danger?

For example, infinitecoin (IFC) is an old coin and only has less 10Mh/s net hashrate (one L3 has 504Mh/s).

[coins4commies]

I like to imagine movie-like scenarios where this could happen.  It could play out a lot of ways.

1. A bane-style attack to strong-arm a large-scale mining operation (or even cloud computing facility) and redirect it to a 51% attack on a coin. 

2. a virus that damages the hardware of opposing mines, reducing hash power required to reach 51.

3. a coordinated effort by a large online group of people  (like anonymous) to gang up and 51 a certain coin.

4. In the future, instead of wars being fought over gold or oil, wars are fought over computing power.  Primary bombing targets would include the largest mining operations.