I have no idea what the blockbuster dvd's / blurays sell on average per title, but I'm assuming that they cannot be compared to a sequel series like Halo, MGS or GTA.  (all of those were HEAVILY advertized all around.  I haven't even seen one single sound about the Iron man Bluray over here...)

 You are looking it wrong.  How many threads did we have last two weeks about Blu Ray going to die or is not doing so well? And then we got the news that Iron Man on Blu Ray sells 500k first week.  It is maybe not impressive but it also shows that blu Ray is not dead.

honestly the number listed there, make me feel that blue ray has less of a chance than before. i had expected 1 mill first week minimum for this movie, and 2.5 mill min for the dark knight first week. this lowers my prediction of blue ray only major movies from christmas 09 to christmas 2010, and pushes dvd, to have 2 more major years as king of revenue and king of units, then lose its revenue crown in 2010, and its units crown 2012 (if blueray does take it out) 

@HappySqurriel -- Iron Man selling 500k in one week is good, it also sends a good message about how The Dark Knight will go...

Ultimately though we won't see blu-ray sales looking good compared to DVD for another year or two unless the major studios decide to release movies on blu-ray first. eg. release the film on blu-ray 13th October and on DVD 20th October...

Dark Knight Blu-Ray > 1 million sales first week.

its going to take more than a few weeks dif to set up blue ray afire, more like 6 months, and not announce the dvd release till later. i had originally thought that something like that would happen next christmas, but with these sad numbers,  i dont see it happening until 2010, like i posted above you. not even the digital switch is going to help now. i had no idea how sad blueray sales were 

About the Prices, i don't know about the US but in Europe the BD's still cost up to 40% more than a DVD. Until that changes i don't think the adoption rate will speed up anytime soon.

heck when street fighter 2 special championship edition came out for megadrive, i paid £ 59.99 for it and £ 29.99 for the six button pad all in 1 go, good to see bluray having ok sales, i predict after 2009 the hd adoption will be big, dvd's are shit i cnt see the point in them. the gap from a premium vhs release to a dvd was a big step up on sd tv's, the gap from dvd on sd tv to bluray or even hddvd on a hd tv especially in 1080p is a much bigger increase

I think blue-ray is doing fine and plan on buying a player this year, but these sales numbers are actually not saying blue-ray is doing well but that Iron Man is doing amazingly well. The reason I say that is the ratio of DVD to BD sales of 7.2 million to 500k is actually just inline with what has been happening all year.

Here are some examples of other movies with higher and lower ratios:
http://www.hdtv-news.co.uk/2008/03/28/blu-ray-disc-sales-gain-ground-on-dvd/

EDIT:

HEre is a better link actually:

http://www.engadgethd.com/2008/07/18/nielsen-videoscan-high-def-market-share-for-week-ending-july-13t/

While a few weeks won't give blu-ray amazing sales day 1 it will help and at this point in time movie studios do not want to risk losing millions in DVD sales for small gains in blu-ray sales. Overtime the gap between releases should grow but i think 1 - 2 weeks is a reasonable starting process. Afterall i believe their will be quite a few angry customers looking for movies on DVD and being told the advertising is for the blu-ray version and that the consumer needs a blu-ray player or to return in a few weeks -- and while some will buy blu-ray players others won't or can't. America is in period of finanical crisis at the moment and Europe is headed in same direction. As such its only natural consumers are sticking to DVD at the moment instead of buying the more expensive blu-ray version.