I was re-reading an old essay by Mr Buffett.
The one in 1999 saying forward returns would be low is well known; this 2001 follow-up is a bit less read, but still worth reading.
money.cnn.com - Fortune archive

Incidentally, it ends with the observation that since the economy had grown since his earlier 1999 essay, and prices were lower, better forward returns could be expected. He suggested something in the vicinity of 7%/year (nominal total return) could be expected for long term returns from there. I checked how it came out: rather to my surprise, except for a few lucky end dates around 2007 when the credit boom was under way, someone buying SPY the date of the essay would have had to wait over 15 years before reaching a pre-tax annual nominal total return of 7%/year.

Anyway, the essay talks a fair bit about pension funds, and the rates of returns that are assumed, and how silly and self-serving the assumed rates had been. This led me to find this page, which is a nice snapshot of what pension funds have been assuming lately, and over time.
milliman.com - Corporate pension funding study
Rather to my surprise, the assumed rates have been (except for this past year) on a near-uninterrupted slide since that millennial essay. Maybe some pension managers read the essay?

It's a good read for data geeks. See figure 16 for the evolution of assumed rates of return. It has a nice overview of the biggest DB pension funds by ticker. Berkshire's fund is not one of the largest, at only $13.4bn. Ford's is biggest, at $54.4bn. IBM and GM are comparable.

Jim