New channels are automatically added to the guide unless you are using a favorites list. If you're using a favorites list then you will also not see free preview channels as they are made available.I am super happy! For anyone who doesn't know, Comet is the REAL science-fiction channel, unlike NBC/Comcast's fake and poorly managed competitor Syfy.
I was wondering why I couldn't find Comet in my guide today, but then when I re-added it through the guide menu and saw it was in HD, well, that made my day.
It'd be nice if the Hopper 3 would automatically replace SD channels with HD ones in the guide as they're upgraded. I'm sure there are a lot of people wondering what happened to the channel, and don't realize they have to re-add it to their guide lists.
DISH has the 'All Subscribed' setting for the guide which is probably the way to go if you want to see everything that you get but nothing else.