Home audio & video forum: How often do TV manufactures refresh their line up?

IMHO the '3D' is still very gimmicky and pales to actually buying a display that has the best image quality. Any and or all notions of prioritizing that feature should be thrown out until they actually get it right and its not simply fluff.

Your question is simple enough and so is the answer. Manufacturers of products (particularly tech products) keep producing and releasing new products because technology is always progressing and the inherent law of success dictates that a manufacturer must push that envelop to stay ahead of the competition. As often as yearly, something "New & Improved" comes out. If you are waiting because you want to get the best, then sorry to hit you with the truth. The best you can achieve is the 'best there is, right now' and call it a day. By the time you buy that Top-o-the-line TV, a superceding model is getting finalized for demo at the next CES.

What you should be considering is how much BETTER the next line-up will be, not when. Replacements are inevitable, quality improvements that justify the price are not.
There is always a period when tech seems to plateau. Judging that point is the best time to buy, but keep in mind that it is subjective.
For example, I bought a Sony 46" HDTV in Nov. 2008 and of course the new ones came out by that following spring that were cheaper AND included all the features I premiumed-up for. For me, even to this day, the picture quality has not gotten that much better to warrant me buying another one and the 3D (like you said) needs to get a little better before I pony up. On the other hand, someone may read this and say I am BLIND for not seeing the OBVIOUS picture improvements in the latest Sony line-up.