Terminal behaving differently since updating to Lion
This is the resume feature of OS X Lion.
Undo resume for a specific application
Type the following command in the Terminal. Then restart the specific application.
In general the syntax is:
defaults write com.&quot;producer&quot;.&quot;program-name&quot; ApplePersistenceIgnoreState YES

Thus, in your case (Terminal.app) it is:
defaults write com.apple.terminal ApplePersistenceIgnoreState YES

If you want to set the resume feature again, simply write NO using the same syntax.
Undo resume for all applications
In order to disable this for all applications do this:
go to System Preferences-&gt;General