In some countries (eg. UK) a fault that is due to manufacture or design must be repaired irrespective of any warranty that may or may not be in effect. In these countries Nokia will remain liable for up to something like 10 years - my guess is that Nokia hope the disposable nature of modern phones will ensure their liability is very much limited, but don't be put off should your N900 develop this fault and you're just out of warranty - it doesn't matter, it's still down to Nokia to fix, at no cost to you.