The first of its kind Panasonic LiFi hybrid light source has a 5 Year warranty. For a RPTV light source - that's unheard of.
You probably already know the LiFi hybrid light source is quite different from traditional UHP lamps as they are electrodeless. Electrodes in traditional UHP lamps erode/evaporate over time significantly decreasing light output/brightness. Everytime a UHP light source is used you're essentially burning the candle down; eroding the electrodes, widening the gap, reducing light output and driving the lamp towards self-destruction. The inherent design of such bulbs yield an unavoidable short lamp life.
When manufacturers quote the "life" of a light source in hours (i.e. 3,000 hrs) it means the number of hours at which 50% of the bulbs in a "population" of bulbs will fail. From what I see, UHP bulbs are rated for 2000-5000 hrs (and cost approx $300 to replace). The Luxim.com website says the LiFi (4000) lasts up to 5X as long as traditional light sources, meaning they should last the life of the TV.
I recently read a blog coming out of Vegas/CES 2008 that discussed the current "deal" RPTVs represent to consumers, even in the face of declining prices on LCD and plasma displays. The Panasonic LiFi PT-56LCZ70 was specifically mentioned along with a sub $1000 retail price. I just looked on Amazon and they're selling the 61" 1080p for the same price as the 56" 1080p (under $1300). Dollar for dollar and inch for inch I don't think you can go wrong with the Panasonic LiFi TVs.
Check out the user comments on Amazon.com. The vast majority give the Panasonic LiFi HDTVs high ratings on price/value (putting money in their pocket over similarly sized LCD/plasma displays), brilliant stable color, nearly instant-on start times, and the prospect of never having to change the lamp.
Do the heavily-touted Panasinic Lifi bulbs (found in their DLP sets) really live up the the promise that they weill never have to be changed (a $300 USD purchase)?
I am currently considering the 56" DLP Panasonic model and this is a major factor in whether I make the purchase or not (its other specs seem quite good, e.g. 3000:1 contrast ratio, 1080p, etc.)