I agree that some sort of persistent voicemail indicator (message waiting lamp, MWL) needs to be implemented and that Benny is correct in his belief that this is not a request appropriate for brainstorm, for the very same reasons he mentions. Contrary to what other posters indicated, in the US at least, this seems to be a standard expected feature. I've used phones from half a dozen vendors on every major carrier in the US over the past several years and every single one has had it. A quick informal survey around my office indicates that everyone here expects a persistent MWL, and perhaps most importantly, this feature exists on the Motorola Droid, which is arguably the comparable competitor to the N900 in this market.
They're maemo and MeeGo... "Meamo!" sounds like what Zorro would say to catherine zeta jones... after she slaps him for looking at her dirtily...