If you have a single player and a shelf full of discs, you are right there with the majority of the public...

As you add automation, you pay for convenience every step of the way...

If you just go out and pick up a Sony mega changer and expect to use the internal DiscExplorer function, think twice about that... It sucks, even if you religiously title your discs and capture the little thumbnail image of the menu as you add them with a keyboard or the long way with the alphanumeric commands on the remote. One power outage and the hard work is gone, many of the Columbia titles will auto-recognize, but the rest of the ones you keyed in are lost...

Next step.
DVD Managers (aka Changer Controllers)
The Escient DVDM and Request VRQ are pretty similar overall, each with their pros and cons.

The VRQ pros: bulletproof IR, serial, and IP webserver control. The graphics are high res. through the component or VGA outs.
Cons: It requires an outboard switcher, and has an interface that is different than their Audio Reqest servers. You have to add your own cover art for the majority of the DVDs you put in, this is easy (you can snatch them from Amazon) but it can be VERY time consuming.
It used to be that you had to attach cover art to everything manually, but I believe they have inked the deals to have some of the studios' artwork auto-load now like the Escient.

Escient DVDM pros: has internal switching, similar interface to the audio version, and the upper models have a HD for a single zone of audio built in. Cover art auto load.
Cons: The IR is seriously improved over previous generations, but is not as bulletproof as the VRQ. The graphics (and cover art) does not seem to be as crisp as the VRQ, they are probably still interlaced.

Having either of these controllers makes life really easy compared to trying to figure out where the Hell the 3rd disc of Sopranos Season two might be located in your changers...
Is it slow?? Compared to a server it is noticably slower, and you are still navigating a disc. Compared to shuttling through a changer or rifling through the media on your shelves, it is a convenient and quick way to access your collection.

As for the servers, AMX Max, Kaliedescape, XPerinet, and Niveus seem to be the major players. Max and K-Scape are proprietary, and seem to be bulletproof at a VERY high cost.

The XPerinet and Niveus stream files that you rip into the internal HD using a third party Codec that you also have to set up. Depending on the quality of the recommended Codec, and how well it deals with the individual discs, your mileage may vary... I would imaging that the studios will be throwing protection fixes at these Codecs as time goes by.

As for HD-DVD and Blu-Ray.
I would speculate that a mega changer would be coming shortly after the single players hit, and with that comes the opportunity for a controller from players like Escient and Request.
Whether they add the new changers to the current controllers, or start over with new models, it should come along pretty quickly.

Servers streaming the high def content will have to deal with the lawyers and the wrath of the Hollywood machine. I would bet that they will throw SERIOUS litigation at everyone who blinks in an attempt to keep content of this quality off of servers and only on the original discs.