Again you're not the first to be confused.  If you had turned autobuild 
off during those 2.5 years, you would have found four build actions in 
the project menu:
Build All
Build Project
Rebuild All
Rebuild Project
The first two were not in the menu when autobuild was turned on. Most 
non-autobuild users have (understandably) never fully grokked the 
distinction between "Build" and "Rebuild".  So, in M8 the "Rebuild" 
action was renamed (more or less) to "Clean...". So, with autobuild off, 
you now get:
Build All
Build Project
Clean...
This is (hopefully) clearer to non-autobuild users. Most autobuild 
users, who had never seen "Build All" and "Build Project" before but 
were used to seeing "Rebuild All" and "Rebuild Project" now get the 
impression that actions that were previosly always enabled are now 
disabled.  These are in fact completely different actions. "Clean", 
which is the M8 replacement for the "Rebuild" actions, is still always 
enabled. I am planning on now reverting to the old behavior of removing 
the incremental build actions when autobuild is turned on.  You will 
then only see "Clean..." in the project menu.  For an even more 
long-winded explanation, see:
http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/platform-core-home/documents/scoped_builds.html 
John.
platform-ui-dev-admin@xxxxxxxxxxx wrote on 04/13/2004 04:41:20 PM:
 >
 > Now I'm really confused. AFAIK, I've had autobuild on for 2 1/2 years
 > and those items have always been in the menu.