The wrong people in the wrong place
> a willingness to engage in small, experimental, IT projects rather than the larger endeavours
I have only worked in one startup - and that hit the wall after 6 years.
However, comparing the attitudes there with those in larger, established companies I can't see the concept of "internal VC-ing" working very well.
For a start, the factors that attract workers to large companies: stability, lack or slow change, lots of structure guidelines processes and procedures and a nice easy 9-5 are not the features you get in startups. You also find that a lot of the large-company workers are willing to trade a lower salary and prospects for all the factors listed above - plus a pension.
In startups you want exactly the opposite sort of individual: self-starters, working 5 - 9 (a.m. to p.m), a JFDI attitude to problem-solving, and no two days being the same. People who thrive in that sort of environment will not usually be found working for MegaCorp. (They'll in the industrial unit down the road).
And finally you have the shareholders. People who invest in large, stable companies want large stable returns - not a 90% failure rate. So it might be trendy for CIOs to embrace failure and be able to excuse it with one, occasional, win. However, would they last long enough in the position to deliver that one win in ten? And if they were "VC" material, they'd probably use the large company as a training ground - financing all their costly mistakes and then when the success does come along, be off like a shot "to spend more time with their money" and open a startup of their own.
If large companies want innovation and want it quickly, they usually simply buy the relevant VC-funded startup and assimilate their technology. Much less risk, appears on the books as "growth" and can you can see what you're getting into before you open your wallet.