Some good takeaways here, and an inspirational message, but the human brain still has a reasonably fixed (over the long term) bits per second acquisition/retention rate for pure information and a fixed degree of neural plasticity.
In reality, there is a speed limit. At least until Kurzweil gets his way.
By that qualification, the Autobahn has a speed limit too: the limit of how fast land vehicles can move.
The analogy of the blog holds. Infinity only happens in calculus, so why bother poo-pooing a helpful metaphor?
Like a good vision statement in a business plan that calls for a direction without bothering with a specific magnitude, "There is no speed limit" calls the reader to question limitations as a matter of directing their imagination to the problem of expectation as opposed the conventional expectation.
Technically speaking, every stretch of road ever built has an inherent speed limit. Design speed dictates design parameters such as length of sight lines and radius of curves; exceed it too much and you will meet the real limit even if your vehicle has plenty of power left.
For any given vehicle, the design of the highway given the design of the vehicle will impose a speed limit, which may be lower than the limit of how fast land vehicles can move, and may be lower than how fast the particular vehicle can move.
The analogy does hold for the purposes of a fluffy motivational blog post, of course.
I wouldn't trust the strong version of the accelerating change hypothesis. Actually augment our intelligence, or at least our speed of thought probably require major breakthroughs in neuroscience and relevant fields in engineering, which may occur as not-so-predictable quantum leaps.
Plus, there the safety problem: if we ever enhance someone's intelligence, we may want to make sure that (i) it doesn't make him mad, and (ii) the guy doesn't plan to take over the world. The proper sanity checks may require yet other breakthroughs.
Also, change in technology may find itself outstripping society's ability (or willingness) to integrate it. In fact, I'd say it already is, and has been for quite some time.
We have the technology already to facilitate incredible intelligence - it's just extremely unevenly distributed, and stifled by lack of political will and social inertia.
In reality, there is a speed limit. At least until Kurzweil gets his way.