When you create announcements with the announcement editor, it creates a
file that you cannot open directly with IE or Windows Explorer. It
usually looks like a zero-byte file with a name like a timestamp + the
author... something like 42920021124DOMAINusername. I believe all the
data about the announcement itself is stored in the metadata of the
file.
However, you may want to do what we do -- we create an accouncement-type
of file (with our company letterhead, using a template) and save it as
.mht. I save it in the /Portal Content/Announcements folder, then
change the metadata to list the Title and Abstract.
Whammo! The announcement shows up just like all the others, but when
people click on it, it brings up the announcement I created, with logos
and stuff, and the other good part of it is that email notifications
work. They can click on the link in the email.
As long as you have the Announcement profile on the document, it'll
still act like an announcement with start/end dates, etc.