Regarding getting a Brooks (or any other leather item) wet - I don't worry about it, as long as the item is treated with some sort of "waterproofing". After all, we all wear leather shoes and boots, and think nothing of them getting wet when it rains. Look at hiking boots and the abuse they receive in wet weather!
Regarding a Brooks saddle, I think the best advise is not to ride the saddle after it's been exposed to a soaking rain. Riding it in the rain shouldn't really hurt it - your butt is keeping most of the rain off of the top, and the bottom can be protected from splashes by either a seat bag, a rack and trunk bag, fenders, or even stuffing a plastic WalMart bag up under the rails. Riding it when the leather is soaked through, however, will certainly cause it to stretch.
As a side note, a century or more ago bootmakers didn't make lefts and rights, they just made 'em in certain lengths. When you bought a new pair of boots you "broke them in" by standing in water until the leather was soaked through, then wore the boots until they dried. Anyone who's been in the Marine Corps can probably tell you that on about the second or third day of boot camp, your DI marched the squad through standing water, then told the recruits to not change their boots until the boots were completely dry - did the same thing.
(I recently mail-ordered a cheap pair of leather boots that were totally uncomfortable - I needed leather high-top boots that could be laced tightly for ankle support for service rifle competition on the 600 yd offhand (standing) stage. These boots had absolutely no "cup" for the heel - the back of the boot was totally straight. I took them down to the laundry tubs, filled it with about 8" of water, immersed the boots and held them underwater until they were totally soaked, dumped out as much of the water as I could, then put 'em on, laced 'em tight, and wore 'em until dry. In no time the leather stretched and conformed to the shape of my feet, and I had to keep re-lacing them to keep them tight and stretched. After drying, I treated them with a coat of polish, and now they're quite comfortable.)
I wouldn't get too stressed about the Brooks. After all, they're made of leather, which used to be the outside of a cow. Where I come from, cows stand around in the rain all the time, and I hear no complaints from them.
Last edited by tpelle; 08-19-08 at 08:33 AM.