Fortunately for you I generally can show my reasoning on the things I put out there :-) In this case there was data from the Apple vs Samsung trial [1] which if you recall said 775k Galaxy Tab's generated 325M$ in revenue. Doing that math gives you about $448 per tablet in revenue. iSuppli calculated the original Galaxy Tab cost Samsung about $214 to make. That would suggest a gross profit in the neighborhood of $234 per tablet. I was assuming that there was some sort of "OS/License" fee on top of that which is why I didn't suggest it might be as high as $200 each.
[1] "Samsung sold 725,000 units and generated $325 million." - http://news.cnet.com/8301-13579_3-57490740-37/samsung-tablet...
[2] "When the $9.35 manufacturing cost of the Galaxy Tab is added in, the combined materials and production cost amounts to $214.57." - http://www.isuppli.com/Teardowns/News/Pages/Samsung-Galaxy-T...
That's a very different case to the much more aggressive pricing used for the Nexus 7 (publically stated to be selling with no margins) and the Galaxy Nexus. And the new Chromebook too, come to think of it. I guess it's possible that they're switching strategies again. So yeah, if these are priced at $600, I'm sure there's a healthy margin on the few units they manage to sell. But until prices are announced, I see little reason to think that there is such a strategy change.
$150 in "profit" per tablet is beyond ridiculous. I have no idea of where you could pull a number like that from. The common wisdom is that the gross margin on Nexus hardware is around 0. Google's cut from what little content they manage to sell can't amount to much. And the incremental ad revenue from the average Android tablet user isn't going to be more than a few bucks a year either.