Once upon a time, pundits debated whether the PC or the TV would rule the digital home. Now it's clear that both will, along with a ba-zillion other gadgets jumping into the mix from every direction. The digital house party is getting so crowded that sometimes even the various interoperability standards don't work together.

It's a time of fragmentation in these heady days of transition to digital media. The networking standards are fragmented. The security standards are fragmented. Linux has more variants than you can count, and plenty of nagging issues are still getting sorted out in areas like remote access and quality of service.

As the digital home matures, some things will get better--and some may get worse. The difficulty of linking diverse systems will rise as those systems try to enable more user scenarios and thus take on more complexity. "The No. 1 challenge is to enable interoperability across a range of platforms where consumers can enjoy content," said Brendan Traw, chief technology officer of Intel's digital home group.

"There's a huge set of things engineers have to put in place--digital rights management, media formats--and you have to have all the pieces implemented before the content flows," he said. "If any piece of the puzzle is not present, it doesn't work."

At least three major efforts are trying to address interoperability in the digital home--the Digital Living Network Alliance (DLNA), the Universal Plug and Play group (UPnP) and Intel's Networked Media Product Requirements (NMPR). The programs are roughly coordinated, but have their gaps and areas of overlap.

The situation is similar in many other digital-home areas ranging from security to display interfaces. "It's not clear to our customers which standards will win, so we have to support them all," said Brad Dietrich, chief technology officer of Mediabolic (San Mateo, Calif.) a maker of middleware that tries to patch together the pieces for consumer systems. "You will not have good interoperability coverage if you just write to the spec," he said.

For example, "a lot of things consumers come to expect from a DVD player, they can't necessarily expect from devices working over a home network," Dietrich said. "Packet-scheduling implementations are not in any standard, so there is no guarantee the media playback works between different devices. You don't even know whether you can support trick modes like fast forward and rewind."

That could be one of the reasons that as many as 40 percent of all Wi-Fi access nodes get returned, said Alan Messer, a principal engineer who runs a home networking R&D lab at Samsung and chairs the UPnP steering committee. The rise of IP-based TV services will add new complications as content based on Web formats hits consumer systems on home nets. "As devices get more complex, they need new levels of interoperability," said Messer.

Plenty of companies like Intel are pushing the envelope by trying to dream up new user scenarios. For example, this summer Intel hopes to announce work with various industries to let users burn protected content on an optical disk that then can be played back not only on a PC, but on any existing DVD player. That's just one of at least four new scenarios Intel is trying to enable for its Viiv home PC platform.