vim doesn't do this, but I'm not sure about the others. However, there's a very simple way to check this:
Open up two terminal windows (konsole, gnome-terminal, etc), and run the following commands in the first console:
touch ~/test.txt
vim ~/test.txt
Now, in your second console, type the following:
echo "This is a test" >> ~/test.txt
If the file is locked by vim, your command in the second console will fail, as the file cannot be written to. It won't fail. Repeat with whatever editor you want as step #2 in the first console.
Obviously, if you try and save any changes in your first console, you're wandering into uncharted territory, but as far as appending to log files go, this is safe.
Some editors, such as vim, gedit and others, create a "shadow" file when opening a file to indicate that the file is open in the editor. This is not locking, and does nothing to other applications on your system - it merely serves as a way for the editor to know that the file is open.