I finally found the actual transcript of the voir dire part of the case mentioned in the question.
As can be evidenced from the transcript, the judge has specifically instructed the two jurors working as engineers at the local tech companies that they'd have to "forget" what they know about both the software engineering and the patent law itself, too, starting their work on the whole case with a completely clean sheet, using a very simple criteria for making decisions:
One side or the other is going to have the burden of proof on -- one side has the burden of proof on some issues, the other side has the burden of proof on other issues. When you go into the jury room to deliberate after you've tried your hardest to understand the evidence, if they haven't educated you on it or if they haven't persuaded you, the party with the burden of proof loses. It's that simple. You don't have to -- you have to make a good faith effort to understand it, but if the party with the burden of proof has failed to do that, the party with the burden of proof loses. That's the standard. You have to -- you, the jury, decide.
Now, what you cannot do is bring to bear something that you've learned in some other case, some other patent case, about how some piece of equipment works or something like that. You can't do that. It has to be based on the record here.
Then, after a short break and a consultation with the lawyers, where Oracle seems to have expressed some concern to having the computer experts be on the panel, which subsequently prompted the judge to declare the following to the two potential jurors who worked at Cisco and HP:
So this is really going to be directed at both of you, but, you know, you come to the party, so to speak, with some prior training that bears upon the subject matter we're going to be hearing a lot about here. That's okay. That's not disqualifying, but you -- it's okay to use your common sense when you render a verdict, but you cannot add to the record in court something that you know about the way software programming works that the witnesses didn't actually testify to. You see what I'm saying?
You've got to decide the record -- the case based on the record made here as opposed to adding into it what else you may have known about the way programming and software works.
Since both jurors had so much software and patent experience that they couldn't disregard it easily, they were thus both excused (page 95 of 224).
All right. I think it would be too hard
for you to sit in this case and sort out what you knew already
against what is proven or not proven here, and itwould not be
fair to the parties to have that extra burden even though you
two actually know something about the subject. It's in a way
too bad, but it's for the best. So you two are excused to go
back to the jury assembly room. Thank you.
The other instructions that the judge gives to the potential jurors is also worth reading (starts on page 36 of 224)
The full transcript is at http://www.groklaw.net/pdf3/OraGoogle-942.pdf.
In summary -- jurors are only allowed to talk to one another when the deliberation process starts, and, no, they are not allowed to bring any "baggage" to the case at stake.