Warning: Spoilers included. Please watch the movie
first. This is the best movie I've watched for a very long time -
on par or better than The Matrix.
I like the part of Inception where they talked about how an idea
when planted very deeply (similar to what Thusness said - it has to
be planted very deeply) into the subconscious will keep manifesting
itself in the conscious life.
This is precisely the importance of the Buddhist teaching of the
8th Consciousness. It applies to karma and habitual tendencies.
Even the enlightened beings can't escape this (unless they have
reached Arhantship and thus freed from samsaric cycles) - they have
to plant the seed of anatta and emptiness so that when they are
reborn in next life, the seed will grow and manifest easily. Also,
when the seed is deeply penetrated, so deep that it replaces all
the dualistic/inherent tendencies lying deep into our subconscious,
it will persist throughout all three states of waking, dreaming,
and deep sleep. That means one will experience no-self and
emptiness in all three states.
This also explains why if you keep chanting, one day you will
continue chanting even in dreams. It's already placed in the 'safe
house' so to speak, and I like how they use the 'safe house' or
'store house' as an analogy in the movie - precisely what the 8th
consciousness is called. (I'm referring of course, to Cobb's wife
Mal, who Cobb spinned the totem in the safe house so that Mal keeps
thinking that the world is unreal even when she wakes up because
the totem keeps spinning in her subconscious mind - as an imprinted
idea)
Also, what they said about dreams is very true - in dreams, the
people/things you see are a symbolic manifestation of your
subconscious psyche (this part our moderator Simpo is an expert on
and is able to gather information from dreams very well - though I
don't think he can steal your subconscious unless you tell him
about your dream contents 
), and you only know
you are dreaming when you wake up on hindsight (well unless you are
lucid dreaming).
p.s. I wonder if people have came to the conclusion that
actually the whole movie is a dream from beginning to end (Mal: "Do
you think you’re living in reality? Being chased around by
anonymous corporations all the time?")
update: just found a comments online -
A truly excellent piece Devin... Like one of the other
posters I have never been to this site before and found it a
wonderful piece of synchronicity to have come across it only days
after my first viewing of Inception. I will be going back for a
second and maybe third viewing, but as of now I am pretty convinced
by the “it’s all a dream” argument. I found (as some others did)
that Mal’s asking Dom whether he really believes he is being
pursued across the globe (and similar urgings for him to “wake up”
that come from Michael Caine’s character) are like rational voices
trying desperately to intrude into a paranoid schizophrenic’s
delusional mind-set. The whole escape from the failed extraction,
including the approaching rioters (a flood of uncontrollable
feelings to be evaded?) and walls that felt like they were closing
in (a classic panic attack?) seem to me to fit that interpretation.
Though I am also impressed by your analysis of the movie as a
representation of Nolan’s process of directing a film, it is of
less interest to me than a possibly even wider frame – that what
Nolan is addressing (with or without full awareness) is the nature
of consciousness and the construction of reality itself. Key to
this interpretation is your point about the meaningfulness of the
catharsis that Fischer undergoes in the fortress – that “despite
the fact that his father is not there, despite the fact that the
pinwheel was never by his father's bedside, the emotions that
Fischer experiences are 100 percent genuine”. It made me remember a
favorite line from one of a series of books of “channeled” wisdom
from the 1970’s, in which “Seth”, the channeled entity, said of
human experience: “It’s not real, but it does matter”. The idea
that he was presenting was that our experiences in this life,
though not real in any concrete sense, are an educational process
of great importance. Hindu reincarnational beliefs take a similar
tack, and the Buddhist view that “all is Maya” – i.e. illusion –
are another part of the same map. In fact, they say that you can
only “get off the wheel of reincarnation” when you fully “wake up”
from Maya. So for now I will consider this film another meditation
on that theme; and ponder how “breaking up is hard to do” (Dom and
Mal) is related to “waking up is hard to do”. P.S.: Speaking of
paranoid schizophrenia, was that the Cabal corporation that Dom
failed and was being hunted by?