Reading the article gives quite a good insight on how those spammers work: They don’t seem to really request the page of your entry, but they only submit hardcoded values in some database.
This gets this seemingly simple trick to work. Inststead of reading the weblog page and submitting the real form, spammers still submit the hardcoded value, missing the additional form-element.
Unfortunately, this problem is easy to fix for the spammer: Just update the database with the new information form the forms. And I promise you: As soon as this hack gets more known (which is bound to happen soon as it’s so simple to impelement), they will update their scripts.
The logical next consequence would be to change this additional tag more often, leading to the spammers updating the index more often.
The ultimate consequence would be a script generating some kind of random cookie which is different on every request. This in turn would lead the spammers to actually request the form before sumitting it.
I don’t think, I have to name the consequences of that: The spam will stay, but the bandwidth needed will increase greatly. Instead of just posting, the spammer will also request the whole page.
And the spammer will certainly do that on all weblogs. Regardless of whether they deploy this cookie or not.
So in the end, this “fix” just makes the whole thing worse for all us bloggers.
Sorry. No solution. Or ist it? Convince me otherwise!