To be more specific, he refers to master/slave replica pairs, which have now (since 1.6) been superseded by arbitrarily sized replica sets. Also, MongoDB now (since 1.8) has single server durability due to a write-ahead journaling protocol. The namespace limit is also a bygone limitation as you can now specify the size of your namespace file. There are probably a lot more things in the post that are no longer relevant, but I haven't used Mongo in awhile.
Additionally, most of what is actually relevant (file handle limits, oplog sizing) is now fully documented in the MongoDB manual.
Yes... it took me a while to realize that this was a very outdated article. (It hit me when I read about background indexing which was supposed to be coming in "1.3".. we're now on 2.2.2.
A mod really ought to append a (2010) to this post title.
I think the differences you find can me mostly attributed to whether the DB plan you are looking at is multi-tenanted or not. MongoLab (I'm from MongoLab) has inexpensive multi-tenant plans and dedicated plans (alpha right now). In the former servers are shared (and can thus be cheaper), in the latter you get your own VM (on EC2 or wherever). RDS gives you a VM. I have not clicked on all the links in your post but I am betting that is the main difference in price strata you see.
To be clear, the parent post is referring to the invention of LISP.
As a side note, for those who don't know, JavaScript shares a number of features with LISP/Scheme. JSON has the trappings of the very LISPy idea of "Data = Code". It doesn't quite live up to it though. Now, if we only had a parenthesized syntax for JavaScript...
I agree with the other reasons posted. One more reason is one of expressiveness. When you have a "flat" simple form, it is easy to serialize as name/value pairs and send to the server in that fashion. However, when a form is more complex, with nested structure or with variable-length lists of data, it can be very difficult to come up with a serialization scheme that fits the name/value pair model. Often you end up creating your own mini language. If, however, you use a JSON object or XML node as your payload, you are free to transmit data of arbitrary complexity rather easily. So in cases where the data you want to POST/PUT is not flat, you will have much more expressive power encoding your data in JSON or XML and posting it in the request body.
The point here (in the orig article) was that in some cases you do (i.e. if all you have is a SAX parser - Obj-C iPhone SDK being singled out as an example where only a SAX parser is supplied by the SDK)
6.00 uses python now? :(. Call me old-fashioned but I think scheme should have remained. I feel I really benefited from scheme being my first programming language. Recursion is in my blood now :)
