I want to be sure I have this right. After studying AVS Forum, I believe that there are exactly two ways to get an HD satellite signal into an HTPC:

1) Nextcom R5000-HD modified satellite receivers;
2) Hauppauge HD PVR.

Both connect to the HTPC by USB. However, neither has device drivers for Linux. Accordingly, for a Linux-based HTPC, there is exactly no way to get an HD satellite signal into an HTPC.

You could also put a dvb-s card in your htpc to receive the satellite signal.

I want to be sure I have this right. After studying AVS Forum, I believe that there are exactly two ways to get an HD satellite signal into an HTPC:

1) Nextcom R5000-HD modified satellite receivers;
2) Hauppauge HD PVR.

Both connect to the HTPC by USB. However, neither has device drivers for Linux. Accordingly, for a Linux-based HTPC, there is exactly no way to get an HD satellite signal into an HTPC.

I've seen posts where there are people using both devices in Linux

Some info on R5000 and mythtv that I found with google:
http://svn.mythtv.org/trac/ticket/4752

the HD-PVR Linux driver exists but is early on:
http://www.mythtv.org/wiki/Hauppauge_HD-PVR

There is a thread somewhere here that details Linux experience with it.

Good catch. I was aware of both, but neither seems like a solid solution. The first reads as a patch for MythTV, which makes its applicability questionable in a system running SageTV (as I currently intend) -- or anything else, for that matter. The second is alpha quality, which may be a bit too unstable for some of us. Things seem to be moving in the right direction, though. I really was wondering whether there was something fundamentally different that I had missed -- like a plug-in card with an HDMI input (which is clearly the way this problem should be solved). I don't think that a generic dvb-s card is a solution because each satellite service surely has its own encryption to protect its signal. DirecTV announced its own PCI card about 2 years ago, but it never came out. Pretty easy to guess why. Too bad, though.

there are HDMI plugin cards (last I checked they cost more than the HD-PVR though) but obviously they won't work with HDCP protected content. I was told the direcTV DVR I have (HR21-200) actually doesn't have HDCP enabled (but they can at anytime of course). There is simply a conspiracy to lock out Linux (and windows in many cases) users from easily transferring content.

Also are the modified sat tuners --> http://www.169time.com/; but they're expensive, and I really haven't heard any feedback on them.