In many classrooms that I visit, there are three or four classroom computers, and they are on tables pushed up against a wall on one side of the room. Often the computers are used as an extra center, a project station, or as a reward.
Several years ago, I learned about the Inspired Classroom model which brings four or five classroom computers from the perimeter of the room to the student’s desks/tables. The student desks/tables are arranged in small groups that allow students to work cooperatively, and each group has dedicated access to a computer throughout the day.
This arrangement allows the technology to become an integral part of the learning process. Short of a 1-to-1 environment, the Inspired Classroom model goes the distance in getting the technology in front of "most of the kids, most of the time," and seamlessly integrated into the teaching and learning process.
To find out most about the Inspired Classroom model, check out this wiki.