Some brief notes from a Mac OS X perspective:
http://www.wuala.com/grahamperrin/public/2009/04/11/evernote-fsc-001.png for an fseventer view of file system changes when Evernote Web Clipper in Safari produces a PDF, launches the main and helper applications, and syncs.
No evidence there of Sync Services, which may be surprising given the otherwise fine use of available technologies.