Not so. In order to vote on a nominee, the delegate must have been selected thru the primary process, i.e., the ballot box. There are some Reps who attend the Rep convention based on certain rules and they can participate in drafting the platform, etc., but they cannot cast a vote for a candidate.
Then who, exactly, are the delegates from Arkansas, Minnesota, and Illinois on this page: http://www.cnn.com/ELECTION/2008/primaries/results/scorecard/#R
Actually, there seem to be far more than I had thought there were. From that page:
“• There are currently 2,380 total delegates to the Republican National Convention, including 1,917 pledged delegates and 463 unpledged delegates. The total number of delegate votes needed to win the nomination is 1,191.
“• Unpledged delegates in the Republican Party do not have to indicate a candidate preference, but a majority are elected just like pledged delegates. Of the 463 unpledged delegates, 123 are RNC members who become delegates automatically. “