Q:

Is there a meteorite from Earth on Mars?

No body is immune to impact by other bodies. Earth too is no stranger to body-play; Micro-micro meteorites accumulate by the giga-ton annually in the form of dust. Larger impact bodies such as the Chicxulub capable of delivering as much as 100 Teratons equivalent of TNT are also out there - but less frequent. As many as 132 meteorites found on Earth are identified as of Martian origin. 

On October 17, 2013, NASA reported, based on analysis of argon in the
  Martian atmosphere by the Mars Curiosity rover, that certain
  meteorites found on Earth thought to be from Mars were actually from
  Mars.

Back in the 1960s/70s, Project Orion was a theoretical study on a nuclear pulse propelled space-ship. Several devices being flung out opposite to the desired direction of thrust. Each device imparting an absurdly humongous specific impulse on detonation. 
What I therefore find myself wondering 

How large would the impact have been on Mars to impart escape velocity to the rocks that eventually turned up on Earth?
Even given the turbulent environment on Mars, is there a possibility one of the impact craters - the source of an eventual martian meteorite, may be discovered by one of the missions presently on/under-way to Mars?
Is there a probability of discovering a Venerean meteorite here on Earth? 
Could Chicxulub, or a comparable impact have imparted escape velocity, or larger to a rock such that it would eventually wind up on Mars, or Venus?

A:

The majority of the rocks from Mars appear to have come from a single impact on Mars, which formed Mojave Crater. I'm finding it difficult to get an exact power for that impact, but the crater is 58 km in diameter. It is a very large crater, one of the type that rarely impacts anywhere.
Discovering a Veneran meteorite would be quite rate, as LocalFluff mentioned. It's not impossible, but it would have to be the result of a very large impact, which seems unlikely. It is likely there is rocks from Venus around, just that they are likely buried after a long time in the past.
It certainly is possible that a rock from Earth could have made it to  Mars, but that isn't all that likely. Most likely, any such rock would be from the Late Bombardment period, as that's the only time in Earth's history with such power, at least, with Earth as we know it. I have little doubt that the impact that resulted in the Moon showed the solar system, however, it is unlikely that many of those fragments have continued to survive, except perhaps in deep space.

A:

There should be. It needs a huge impact on Earth to send material all the way to Mars but we get them occasionally. You need something of the order of the Chicxulub impact 66 million years ago. The debris would take about a hundred years, for the first material to get there and the material would continue to arrive on Mars for up to 20 million years from that date. So probably the youngest meteorite from Earth would be over 40 million years old.
Though you didn't ask it, but to follow up on the other answers, it is very hard to get meteorites from Venus to Earth. The problem is the thick atmosphere. An impact like the Chicxulub impact would send meteorites to Earth if its atmosphere was similar to Earth's. But with its thick atmosphere, it would need to be much larger. And from the impact history on the Moon, Mercury and Mars then the larger 100 km scale impacts all date back to well over 3 billion years ago.
However way back then, then Venus might also have had a thin atmosphere. So there could be Venusian material on Earth, a bit of it, but it would be impossible to recognize after all that time and weathering. But if this is right, then it's probably there on the Moon, and much easier to spot as it wouldn't be weathered, and there might be Venusian meteorites on Mars.
There could also be Mercurian meteorites on Earth - and Mars also. Mercurian Impact Ejecta: Meteorites and Mantle
I think the best place to look for Earth meteorites is on the Moon. If they landed in frozen areas of the Moon, they may preserve organics from millions or even billions of years. They could also preserve fossils as fossil diatoms are still recognizable, and the smallest ones intact after a simulated impact on the Moon. There may be as much as 200 kilograms of material from Earth per square kilometer of the lunar surface. Details see my Record keeper of inner solar system (including astrobiology and early life on Earth)

A:

- Is there a probability of discovering a Venerean meteorite here on Earth?
Possible but unlikely. No (known) venerean meteorite has been found on Earth. Several factors make it much more unlikely than a meteorite from Mars (I should write "much less common", certainly some are around, but so few that we might never find them). Venus' deeper gravity well and shorter distance to the Sun turn meteoroids away from Earth orbit. And the thick atmosphere of Venus slows down ejecta.

