How does anyone know this? Are you looking at the SSD option in the MBA? Does anyone have the new 17" upgrade option yet?
If the new 17" MBP comes with a SSD it has to be GSkill, Super Talent, FileMate, or Samsung.
So far, those are the only brands with a 256 SSD drive out. Of course this is constantly changing really fast, so by the time you read this there might be more out. However, I think Apple will be sticking with a major manufacturer/supplier instead of smaller one which in this case will probably be Samsung (I'm just speculating on this however.)
Now, all of those 256 SSDs are in fact MLC. The reason is that since MLC technology is cheaper, it makes more sense to manufacture and then sell drives with such technology instead of the way more expensive SLC.
That's why (so far) you will only see lots of SSDs with higher storage capacities but with MLC technology, and only a few SLC drives with small storage capacity.
I also would like to restate, in a broad and simpler sense, a few things already said:
It is true that MLC technology is cheaper than SLC, but it is also slower and more prone to errors (which accounts for its reduced lifespan compared to SLC). That's why MLC is used more. However, high quality manufacturers such as Intel and Samsung have been developing better drive controller circuits for their drives with better algorithms for better and more efficient cell use. This dedicated development from those manufacturers plus high quality MLC NAND flash memory allow their drives to perform and last nearly as well as SLC drives but with the benefit of being cheaper.
With that said, if your new 17" MBP comes with a 256 GB Samsung SSD you can rest assure that it is gonna perform really good.
Oh, and by the way, there is only one 256 GB SSD drive from Samsung so far, and it's of course MLC. This means that if Dell is offering a 256 GB Samsung SSD for $400, and you paid Apple $900 for a 256 SSD, and your MBP comes with a Samsung, then yep you got ripped off. However, if your MBP comes with another brand like the ones I mentioned before, then you got ripped-off even harder because those drives cost right now around $500 at newegg.com and wont perform as fast as the new Samsung drive.
Sooooo.... my recommendation for those who already ordered their new 17" Macs would be to cancel their orders if they still can and then make a new one but this time select the cheapest hard drive and then wait until Samsung makes its new drive available for retail.
Like some said before... Always build the most basic Mac available then buy your upgrades somewhere else. And for that guy who said that the new 17" MBP can't be upgraded because of its non-replaceable battery let me tell you that, while it wont be easy, it will be possible. You can try to figure out how to disassemble your mac yourself, but if you are too lazy or you don't want, then you can wait until someone figures it out and post it on internet as a guide or as a video on youtube.
I used to have a 24" - 3 ghz iMac which (apparently) you cannot upgrade its hard drive. However, with the help of one of a ton of guides on internet, I was able to change its cheap 500gb with a new faster Velociraptor (albeit smaller in capacity). Later, when I decided to sell it, I followed the same guide again to extract my Velociraptor and replace it with the stock 500gb drive.
If this sounds too complicated for you, or you are too lazy, or you just have tons of money to burn, then I guess paying the $900 that Apple ask you to hand them will not be a problem at all.
How do we know this? Well my friend, there is a plethora of information all over the internet. For starters, I recommend you google as your new best friend. There is also wikipedia which will give you a general idea, and then if you want to delve deeper you can go to anandtech.com or to tomshardware.com
There are plenty of other sites with more detailed information, I just gave you some points to start.
