Apparently, Oracle did not like the documentation of OEM GC 11.1 being published before the official Announcement Day April 22nd.
The link to the documentation of OEM GC 11.1 is not working at this moment.
I am afraid we have to wait for April the 22nd.
But if you are that eager to read more about the new features open you internet browser and search for: e11982 “new features” 11g. You can read the NF using In cache.
Unfortunately when searching on this criterion, you end up with the same URL (that was withdrawn).
But did you use the In cache option? Works in IE and Chrome.