I was reading a post about Visual Studio refactoring support in the next version, and I noticed that it described the process of refactoring the order of parameters for a function as something like this:

1.      click on a function name

2.      select refactor->reorder parameters from the menu

3.      adjust the ordering on a dialog that pops up

4.      click OK to apply the changes everywhere

This seems unnecessarily cumbersome to me.  The same post talks about the existence of “smart tags” in the UI.  You should be able to grab the smart tag for a particular parameter, and just drag that parameter into a different position in the list.  This should do the full refactoring, including fixing up all the calls to that function.  You should be able to grab the smart tag and “throw it away” too – just like you can do to column headers in Outlook.  That would do a “remove parameter” refactoring.