I participated in a thread last month that I thought was interesting and worth noting here. It seems that Microsoft will be moving away from using ObjectTypeCode / Object Type Code in future versions of Microsoft Dynamics CRM and they are recommending that entity name be used for all dependent code from here on out.
This is stated in the thread by Danial Cai (MVP), and then later confirmed by Rich Dickinson who is an employee at Microsoft later in the thread.
You can read the entire thread here: http://social.microsoft.com/Forums/en-US/crmdevelopment/thread/7441b27b-bbb8-4693-876a-de64263aa137/
So you might not want to use ObjectTypeCode in any future customizations as we don't know for sure that it will even be accessible in future versions of CRM.
Have a nice day!