Earlier today, while testing another 10.5 hint (not yet published), I ran into something that's quite disconcerting, and could potentially lead to some lost data, if not just a lot of confusion. In a nutshell, here's the problem, which I've verified in both 10.4 and 10.5...
Say you've got Mac1 and Mac2, and you've connected to Mac2 from Mac1. There's a folder on Mac2 that you use regularly, so you make an alias to it in your Hot Stuff folder in Mac1's Documents folder. To make accessing it easier, you then do the obvious thing, and drag it into your sidebar. But you want to know that folder's on your remote Mac, so you control-click on it in the sidebar and choose the Rename option from the pop-up menu. You rename Projects to Projects - Mac2. When you do that, you've just renamed the actual Projects folder on Mac2 to Projects - Mac2!
The entry in the sidebar is, basically, a direct connection to the remote folder, not a representation of the local alias you created. And while my example is relatively harmless, consider if I had instead created an alias to my user's Library folder on the other Mac; rename that, and you'll find all your settings missing on Mac2 (as the system will create a new Library folder for you as soon as it needs to work with it again). They haven't been deleted, but you'll be quite confused for a while, to say the least.
I made a (somewhat confusing) movie of this process, just to demonstrate how it works. Basically, what you'll see is the creation (on the desktop) of an alias from a folder on another Mac, the renaming of that alias folder on the desktop (which works as expected), and then what happens when that folder is moved to the sidebar and (again) renamed.
In short, the sidebar does not treat local aliases properly at all. As soon as you move the alias to the sidebar, it seems as though OS X resolves the path to the original object. From that point on, any changes you make to the filename of the folder are actually made to the original file. This is not at all what I would expect to happen, and it's not what happens with the alias in the Finder. When you rename an alias in the Finder, that name change is local; the parent folder on the remote Mac isn't touched. A local alias in the sidebar shouldn't behave any differently than a local alias in a Finder window. (Things are a bit different if you create an entry directly in the sidebar, by dragging from the remote volume to the sidebar -- I'm not sure how that should work.)
So be aware, if you're using the sidebar to store local aliases of networked folders, do not try to rename those folders in the sidebar (unless you really want the original folder renamed).
Mac OS X Hints
http://hints.macworld.com/article.php?story=20071108160051963