There's one line of logic regarding the Brett Favre speculation that I find sort of silly. The thinking goes that by flirting with Favre, the Vikings are sending mean signals to Tarvaris Jackson and Sage Rosenfels, and that these quarterbacks will be so psychologically damaged that if the Vikings don't get Favre, there will be some sort of major problem.
Jackson and Rosenfels are professional adults. I know being a professional adult doesn't make one immune to anxiety, insecurity, or any other negative feelings. It does mean, however, that despite whatever anxiety, insecurity, or negative feelings you may have, you will still need to make a gamely effort at doing your job. I assume Jackson and Rosenfels will.
Kevin Seifert expresses something like the psychological damage thesis:
"The simple act of setting up a meeting with Favre sends a mixed message, at best, to the two quarterbacks they had planned to pit in a training camp competition. Simply by virtue of Tuesday's story, Tarvaris Jackson and Sage Rosenfels already know they're on the brink of being pushed aside -- at least for one year."
"If Favre walks away, or if the Vikings move on because he won't accede to their requests, Childress would be left with the unenviable task of rebuilding the trust of his remaining quarterbacks."
Before any Brett Favre story started, both Jackson and Rosenfels each knew he was "on the brink of being pushed aside." Jackson and Rosenfels can't each earn the starting job; they were going to compete for the starting job. Both men likely believe they will have a chance to compete for the starting job (and acquiring Favre would mean they wouldn't), but neither currently holds a secure starting job. Certainly Seifert recognizes as much in his concluding paragraph, but doesn't diverge from his thesis that the Vikings have "boxed themselves into" something. But it's not that either Jackson or Rosenfels was sitting in a position of security, and have had that security taken away. They were each in a position of insecurity that became more insecure (or, if you prefer, they are now secure in their knowledge that they will be backups).
If Favre doesn't become a Viking, then either Jackson or Rosenfels will start week one. And I suspect the flirtations with Favre in May will have absolutely zero impact on either QB's on-the-field performance in September.