Word on the street is that the latest update to the Wii system software, which set Wii slot lights all over the country pulsating this week, uses poorly-written update code that can render even unmodified systems into svelte white bricks. The update, which closes a few commonly-used holes in Wii's security (though others have already been found), marked Nintendo's most thorough attempt at closing down unauthorized Wii use yet.

bushing at HackMii, guardians of all things homebrew, explains the problem for the technically inclined (boot2 is part of the Wii's startup process):

Their boot2-updating code (ES_ImportBoot) is not well-tested; they've never updated boot2 on retail consoles before, and in our testing we discovered that it often fails to write out ECC data for the new version of boot2 that it writes. We should expect to see some number of bricked Wiis from this; the code is so buggy that we decided to write our own for the HackMii installer.

While I'm not in touch with anyone who has experienced this myself, I'm aware of secondhand reports, and Nintendo's own tech forums have a few of their own. It's not clear how widespread the problem has been. I've applied the update myself—it's needed to continue access to the Wii Shop Channel—but you might be setting yourself up for a repair if you try it. Consider yourself warned.

Update: Nintendo had posted an announcement on their tech forums indicating their belief this usually occurs with modified systems, but also that they would fix unmodified systems bricked by the update at no charge. However, this offer has apparently been quietly rescinded. The original text of the announcement follows.

Hello,

Some of you have reported problems with your Wii console after updating to the Wii System Menu 4.2. The symptoms most people are describing usually occur when the Wii has been modified. However, some of you also mention your system has never been modified.

We'd like to help get your system working properly again. If you're experiencing problems with your Wii console after downloading Wii System Menu 4.2, and you believe your system has not been modified, please give us a call. If we find that you have a normal system and the update caused your system to not work, we'll repair it at no charge.

Please call our Customer Service Department at your earliest convenience, 1-800-255-3700. We are open 6 AM to 7 PM, Pacific Time, 7 days a week.

Thank you,
NOA_Tech_Jane

You can find the current announcement, which is said to have been updated on 10/2, on Nintendo's tech forums. You can also find at lest one customer's story indicating he was told he would have to pay the full out-of-warranty repair fee, even though he had never modified his system.

In the meantime, we've heard reports of customers being driven to homebrew—which didn't take long to overcome the protections in 4.2—not because they particularly want to run any homebrew software, but because they're concerned something like this might happen to them in the future. It's an interesting development.