You are correct. LCD's are more limited in size, however. What the really great thing about the LC-45GX6U, is that it is 1080P. The bad thing is they are very limited in stock. We only have two of these right now, and we expect them to go fast.
It would be nice to have 1080 in an LCD or plasma although few such sets (besides the one mentioned above) exist. This means no downconversion to 720p or something else which often results in just 540 lines of vertical resolution when unsophisticated methods are used.
LCD is inherently progressive scan, the crystals on a row do not fade or change until the next scan line's worth of picture information is applied. Therefore de-facto de-interlacing of the "weave" variety will be seen if the circuitry does nothing special besides actually using all 1080 rows of crystals.
The incoming source is still 1080i (or 720p HDTV or 480p progressive scan or 480i regular NTSC).
If the aforementioned TV has a 1080i to 1080p de-interlacer as circuitry, that is probably quite simple since no reasonably priced full featured (with 3-2 pulldown recognition & retention) de-interlacers exist. You probably would not notice any improvement over a regular 1080i (native; with all 1080i scan lines) HDTV set.
You would not see a noticeable difference unless, say you were using it as a computer monitor, or as part of a home theater computer setup or using with a DVD player that upscales.
There is also the Samsung LTP468w. It displays in 1080P also. While there is no unadulterated 1080P material out there right now (as far as I know, and I have been wrong before), the natural ability of this display is amazo. With a little love, and the right settings, it would be the envy of the neighborhood.