Starting now you need to give a reason why you are changing someone's karma; being it smiting or applauding. Adding to the upgrade, you have the option to see who changed your karma and why.
To see who has changed your karma, or whose karma you changed, visit your profile.
Additionally, you can have the option to be notified when someone changes your karma. See screen-shot below:
To do so, go to your profile, click on Look and Layout Preferences.
An addition to this upgrade is that once you have changed someone's karma you can now see how many times you have been applauded or smited.
Tip: to see this, go to your profile, click on any of the karma options, there you will see in brackets the total applauds and smites beside the username.