I'm by no means an expert but I have studied a lot of the relevant fields to this topic in college. I know this thread is long dead but since it came up on the front page of google search of the title I feel the need to give my input. I was really into AI and studied computer science in college until I found out that Moore's law is going to hit the atomic barrier before we have enough hardware by reasonable estimates to simulate a brain and there is no clear way to move forward (neither parallel programming nor quantum computing looks like it will save the dream without major breakthroughs that are by no means guaranteed to come within our lifetimes). The situation looks bad to anyone with a skeptical mind.
The same cannot be said of this genetically engineered intelligence idea. I switched to molecular biology and after two years of study it still seems just as possible especially given that in 2009 gene therapy was successfully used to introduce new genes into a genome to cure colorblindness in monkeys and a fatal brain disease in two human boys. Since you're basically inserting a new gene into a random place in the genome, there's always a chance you'll insert into a cancer gene. That's the bad news. The good news is that it works and can be done on adults. I would certainly volunteer for it if I was terminally ill. Also the cancer thing has a lot of conceivable solutions.
You mentioned recursive feedback. This is unlikely. While it is easy to find genes for intelligence that are already in the gene pool, inventing new ones is a whole 'nother ballgame. Not only would it require understanding the mind, it would also require us to invent new enzymatic proteins which, last time I checked, is still a computationally intractable problem. There is definitely a ceiling there that is likely unbreakable even by the first generation of superhuman geniuses. The good news is how potentially genius this first generation of engineered humans would be. It's estimated that there at least hundreds of genes influencing intelligence each with multiple alleles. Notice how even 2^100 dwarfs the number of humans that have ever lived? You can safely bet that no optimal human in terms of intelligence has ever been born.
Even if you don't buy this argument, citing that intelligence genes are simply additive and interact in such a complex manner that even China's statisticians armed with supercomputers can't find the optimal genome, you'd still have to concede that the current smartest humans are amazing beings that outperform the average or even the highly intelligent in remarkably profound ways.
In short, what you suggest can be done right now on adults in a highly sloppy and risky manner with some of the IQ genes we've already found and it's efficacy would be highly variable, depending on the extent to which the gene's influence is developmental.
There are a lot of unknowns about the future of intelligence: artificial intelligence, uploading, augmentation, and so on. Most of these technologies are likely a ways off, or at least far enough away to confound predictions. Genetic engineering, however, presents a very near term and well understood possibility for developing greater intelligence.
A recent news story published in South China Morning and discussed on Steve Hsu's blog highlights China's push to understand the genetic underpinnings of intelligence. China is planning to sequence the full genome of 1000 of its brightest kids, in the hopes of locating key genes responsible for higher intelligence. Behind the current project is BGI, which is aiming to be (or already is) the largest DNA sequencing center in the world.
Suppose that intelligence has a large genetic component (reasonable, considering estimates for heritability). Suppose that the current study unveils those components (if not this study, then likely another study soon, perhaps with millions of genomes). Then with some advances in genetic engineering China could quickly raise a huge population of incredibly intelligent people.
Such an endeavor could never be carried out on a large, public scale in the West, but it seems China has fewer qualms.
The timescales here are on the order of 20 years, which are relevant compared to most estimates for AI and WBE. More, genetic engineering human intelligence seems to be on a much more predictable path than other intelligence technologies. For both these reasons I think understanding, discussing, and keeping an eye on this issue is important.
What are the ramifications for
Of course, there are a host of other interesting questions relating to societal impact, both near and long term. Feel free to discuss these as well.