Most likely a future release will fix this problem. You can fix it yourself, however, if you have the Apple Developer Tools installed.
Right click on the Adium application and click Show Package Contents. Then navigate to
Contents > Resources > Emoticons
Right click on MSN.AdiumEmoticonset and click Show Package Contents.
Open Emoticons.plist using the Property List Editor (double click should work).
Navigate to Root > Emoticons > Sticking Out Tongue.
Select "Equivalents," click Add Child. Add

to the list, save and quit.