Jim, does your year-end estimate of BRK's book include:
1. The investments in the five Japanese trading houses, and
2. The "several billion dollars in profit" (assuming no supercat losses in Florida), that Ajit Jain forecast at the Annual Meeting?

Nope.
I count the trading house holdings as part of the "unknown" investments per share.
In this case, to estimate book for equities not itemized in the 10Q I just estimate that it gave the same return as the average S&P 500 firm when trying to estimate book.
We know how much stock is in the 10Q, and how much the total was at last quarter end, so it's easy to estimate the total (and comparatively small) "unknown" amount. BYD is in there too.
Close enough for rock and roll.

For the underwriting profit, it's nice if it's above average and so is book, but I estimate IV based on an average underwriting profit level, not a good or bad one, which would just make the value estimate volatile.
In this case I used the cyclically adjusted estimate (based on a percentage of float, and as a percentage of premiums earned) as a proxy for estimating book.

Ultimately, I place more weight on my IV estimate than on book for most purposes, though book is a good addition input to short term price prediction even when "distorted".

Jim