Good News: Holding down command when dragging files around the OS X finder causes them to snap to a grid. Admittedly, this was the case in OS 9, too, but:
Bad News: In the OS X, they made the command key a selection modifier (command-clicking on a selected item will unselect it; In OS 9, command clicking on a selected item didn’t do anything), so if you don’t like the grid position a particular file snapped to, you’ll have to let go of command, grab the file in question again, then hit command again and let go of the file, and rinse and repeat.
Gah, irritating and hard to use. See, the thing is, in OS 9, shift was the only key which functioned as a selection modifier. But while shift behaves the same as it ever did in OS X’s Icon view, in Column or List view, shift is a range selector, selecting everything between what was selected and what you just shift-clicked, much like Windows (Of course, if you already have multiple items selected what will actually happen just gets murky…). So they needed to move the toggle selection to another key, and command won that dubious honor. Thankfully, they didn’t try to make shift-clicking behave like Windows in the Icon view, but this just results in a shift-click and command-click in OS X’s Icon view behave identically.
And since it’s possible to select a range of items in at least two other ways (1. click on the first item, hold shift and hit the up or down arrow (Of course, command-up/down doesn’t work for this, because though command behaves as a selection modifier when clicking, command-up and command-down do something else entirely… Damn, still more inconsistencies.). 2. In list view drag a selection box over the range you want. In column view, click in white space between the name and the arrow and drag up or down.), this change in behavior was not necessary, confuses existing mac users, doesn’t behave intuitively in the first place (What should happen if, in list view, you hit command-a (select all), command drag a box across every item but the first and last so only two items are selected, and then shift click an item in the middle? Apparently it selects everything between the first item in the list (which was still selected) and the item you just shift-clicked, and unselects anything that was after the item you just shift-clicked.), and makes other file manipulations more difficult to complete.
Psst, the OS X Feedback page is over here. Go tell Apple to change the behavior of command and shift back to the way things worked in OS 9. As nearly as I can tell, this was an unnecessary change for the worse that was implemented just because “Windows does it that way”.