This is my source:

http://ministries.tliquest.net/theology/apocryphas/nt/herpilat.htm

The letters in the British Museum are dated to the 6th or 7th century.  Which would seem to me to be evidence that they are definitely medieval writings and not actual letters between Pilate and Herod.  The medieval people were very fond of creating christian related forgeries that made the authors a ton of money.  However, I'm tired of wading through all the christian sites that claim this to be definitive proof that Pilate had Jesus crucified.  I'm sure if you searched hard enough you could find a scholastic treatise on the authenticity of the letters.

Well, I don't know that the question of who mentions them is all that relevant. Sure there are some nutters who think that they are something that they are not. Probably the same people who think that Josepheus was not an outright forgery. Realistically, if we are going to debunk the flavor of the day among nutters, I prefer to deal with what they are.

I did a bit of digging on google and I came up with a few tidbits of some possible relevance.

Apparently, there are quite a few copies kicking around. As with all such documents, there are variations. In the process of copying, mistakes were made. Things were added or deleted out of a desire to make the documents conform to the specific doctrine in effect at the time and place of copying and so forth.

Generally, it seems to be considered that the existing text is probably sourced from an original that was written around CE 400 or so. Also, the documents are often gathered together as part of a larger heretical work known as the “Acts of Pilate”. Adding to the confusion, Justin Martyr mentioned a document of the same title that was already extant by CE 150 or so. Whether the documents from CE 150 have any connection to the documents from CE 400 or not is not generally known as the CE 150 documents do not appear to have survived, so they cannot be compared. Even so, the various letters could have, themselves been an addition to the earlier work.

In any case, it also bears noting that the Hebrews engaged in the practice of writing commentary on the “official” scriptures and much of that work was fictional but written to attempt to explain matters that may not have been clear in the accepted works of scripture. If any part of the letters has roots in a source from CE 150 or thereabouts, they could have been started as a midrash.

In any case, having read the link that cj provided, I have to observe that that version of the documents pretty clearly distances Pilate from responsibility over the crucifixion. Coupled with the fact that the documents may have originated right about the same time that the early church was heading in the direction of holding the Jews responsible, I am left to wonder if the actual motive for writing them may have been to support the concept of Jewish deicide.

that all depends on which gospel you read.  there was a strong anti-jewish trend among even first century christians.  the gospel of john is overtly anti-jewish, with big bad roman procurator pilate suddenly becoming a flustered, helpless, good-hearted milksop who is bullied by the suddenly ridiculously powerful sanhedrin into delivering jesus up to their murderous whims.

as for stealing the jews' money, what's really interesting is that in the middle ages usury was considered immoral and beneath christian dignity, so the jews were given control of moneylending by the law of the christian authorities.  then, shortly afterward, they were characterized by the same authorities as a race of moneygrubbing cheats.

Thanks for all the information! 

I know I can count on you guys to give some great insights!