1) The advantage is you don't have to log-in to your account, per say,
and it DOES have read/unread functionality (well, actually, it doesn't
exist yet, so it *will*, instead of *does*).
The use of this would be to allow you to read news and news-groups
sent to your email without the need to access it.
I, myself, see no major advantage to this, but it does have it's pros
over the regular reading method, such as a more minimal layout, no
ads, could work on a mobile device, etc.
2) It's not publicly, it's infront of a very small group of people. LOL.
Other than that, do you really think he's the only one holding more
than one account (hint: read the post following his.).
In addition to that, ever heard of "The Screen Savers"? It's a TV show
in the US, about computers and stuff, and there's one guy there,
called Kevin Rose. Heard of him? Unless you leaved under a rock for
the past 5 years, you should know who he is. Anyway, he mentioned the
fact he has several gmail accounts more than once on the show, and so
has pretty much everyone else on that show.
It's no big deal, and google don't *really* care if you have more than
one. Besides, most people who do use multis, end up using only one or
two in the end.