The disc volume label is all uppercase with underscores. It tends to abbreviate and often has extraneous information (I have one from A&E that ends with _FIX to distinguish from the same title whose audio is screwed up). It is really only a last resort source for a title.
The PCFriendly disk.id file does contain a user-visible title. It is only spottily supported (I don't seem to have one with it here). I have also heard that it is sometimes just plain wrong.
Although there is circumstantial evidence that one is coming, there is no CDDB-like public network database yet for DVDs that I know of. Gracenote makes money by licensing its SDK for use in commercial applications; it's free if the use is free.
All this pretty much leaves us forced to use a local database for mapping the disc serial number into a title. The discussions elsewhere have so far stalled on reaching a consensus on what this database ought to be.
One possibility would be the flat file used by YxY, YXYPlay.dat, which has a simple enough format. However, there are people whose display hardware does not require them to use YxY at all.
Another possibility would be data taken from DVDProfiler. The underlying DVDProfiler network database is valuable intellectual property in the eyes of its authors. The CSV flat file export function from the local database of owned DVDs does not include the crucial serial number field. And that is where the discussion on the DVDProfiler forum stopped. I do not know whether they are reluctant to add it, or just too busy.
It seems like inventing a new database just for title display is a waste. I'm open to new suggestions, too.
As for the other information that goes to the LCD, it is possible to extract some information about the elapsed time when playing by hooking windows messages. It sounds like there is a commitment to enhance the ATI player to provide a formal interface. Hopefully in time this will set a good precedent for the other players.
Similar things are also possible when watching TV. The display can show what program you are watching, when it started, when it will be over, what comes on next. Here again, this is less obtrusive than taking over the whole screen.
Of course, PVR software and EPG databases are also lacking in supported interfaces for this kind of hooking. And it all really needs to be integrated with an IR blaster (like Slink-e) for tuning the STB to premium channels.
All of which gives it the signature HTPC combination of coolness and fragility.