SHAWN - Many times I have been confronted with the question of why Paul uses the wording "they" in when referring to baptisms for the dead. Some people feel that it makes Paul seem to distance himself from the practice. I realize that "they" refers to anyone was doing it or had done it, possibly including Paul himself. Furthermore, I realize that he would not even use the reference to support resurrection if it were a false practice. However, I was wondering if you are familiar with other references in the Bible that use "they" when referring to the gospel or other ordinances that could offer further support.

JOEL - "Else what shall they do which are baptized for the dead, if the dead rise not at all? why are they then baptized for the dead?" (1 Cor. 15:29)

It is evident that even in Paul's day there were saints who were begining to fall away from the gospel; even doubting the resurrection of the dead:

"Now if Christ be preached that he rose from the dead, how say some among you that there is no resurrection of the dead?
But if there be no resurrection of the dead, then is Christ not risen:
And if Christ be not risen, then is our preaching vain, and your faith is also vain." (1 Cor. 15: 12-14).

His words in 1 Cor. 15:29 were directed at those doubting saints, who may also not have understood why some of the more faithful saints were being baptized on behalf of thier dead. I believe it is the more faithful saints who are the "they" he is refering to. Paul was not distancing himself from the practice, he was using the faithful's practicing of the ordinance as proof to the unbelievers of the reality of the resurrection.
I don't know of any other way to explain this. Once you identify who Paul is speaking to and who "they" are, as I have explained above, there shouldn't be reason for further argument. It's no more difficult to understand than the scripture, "Blessed are the pure in heart, for "they" shall see God." (Matt 5:8) Of course not everyone will agree with this interpretation.

Also, I think it is obvious that Paul could also just be speaking in the third person here as in the Matt 5:8 verse, which as you say could include anyone. I think people sometimes assign too much importance on a single word(eg "they") in the Bible, which we can only trust as far as it is translated correctly.
For example, the Smith and Goodspeed translation of the Bible makes Pauls position on the subject a little clearer:

"Otherwise what do people mean by having themselves baptized on behalf of the dead? If the dead do not rise at all, why do they have themselves baptized on their behalf?" (1 Cor. 15:29)

This translation puts it more in the third person, which makes it easier to include Paul as one who could also support the practice. It seems to more clearly explain that, of course there is a resurrection, otherwise why would these people be baptized for their dead?