It looks like Google has reworked their Advanced Search help page. More info on what you can do with the advanced search interface (in plain English) and section on search "operators" (aka syntax)are now on the page. Other changes include:
+ Renaming "~ search", to "Synonym Search"
+ Renaming "Domain Restrict", to "Domain Search"
When I looked at the page a few minutes ago, a link to the Google Cheat Sheet appeared to be missing. The GCS is available here.