In response to Randy's post, I don't have a Ph.D. in history and have more interest in legal history than training, but my sense is that the best and most careful originalist analysis of the Fourth Amendment — written largely to refute Amar's theory — is Thomas Y. Davies, Recovering the Original Fourth Amendment, 98 Mich. L. Rev. 547, 555 (1999) (.pdf link). It's worth a careful read if you're interested in these questions. An excerpt from the introduction:

  [The historical materials establish that] the Framers did not perceive the problem of search and seizure authority in the same way we now do. In fact, they reveal that the Framers did not even use the term "unreasonable searches and seizures" the way we do.
  The historical statements about search and seizure focused on condemning general warrants. In fact, the historical concerns were almost exclusively about the need to ban house searches under general warrants. Thus, the Framers clearly understood the warrant standards to be the operative content of the Fourth Amendment, as well as the earlier state search and seizure provisions. Moreover, the evidence indicates that the Framers understood "unreasonable searches and seizures" simply as a pejorative label for the inherent illegality of any searches or seizures that might be made under general warrants. In other words, the Framers did not address warrantless intrusions at all in the Fourth Amendment or in the earlier state provisions; thus, they never anticipated that "unreasonable" might be read as a standard for warrantless intrusions.
  Perplexing as that omission may appear from a modern perspective, it made sense in the context of the Framers' understanding of the problem of search and seizure. They saw no need for a constitutional standard to regulate the warrantless officer because they did not perceive the warrantless officer as being capable of posing a significant threat to the security of person or house. That was so because the ex officio authority of the peace officer was still meager in 1789. Warrant authority was the potent source of arrest and search authority. As a result, the Framers expected that warrants would be used. Thus, they believed that the only threat to the right to be secure came from the possibility that too-loose warrants might be used.
  The modern interpretation of "unreasonable searches and seizures" is the product of post-framing developments that the Framers did not anticipate. During the nineteenth century, courts and legislatures responded to heightened concerns about crime and disorder by expanding peace officers' ex officio authority to arrest and search. That expansion marginalized warrant authority and thus undercut the premises that had led the Framers to believe that they could control the officer by controlling the warrant. As a result, the new discretionary arrest and search authority of the officer posed a novel threat to the security of person and house.
  In the early twentieth century, the Supreme Court belatedly responded to the new threat to the right to be secure by extending constitutional search and seizure doctrine to the warrantless officer. It was at that time that the "warrant requirement" emerged as a salient issue. And it was at that time that the reference to "unreasonable searches and seizures" in the constitutional text was reinterpreted as though it articulated the relativistic concept of reasonableness-in-the-circumstances.