Although neither of your claims are strictly totally true, I agree you've got a point that Nokia should take notice of.

• The N900 recently got a much needed - if fairly minor - OS upgrade so that demonstrates that it can and does get upgraded. Much remains to be done though...
  
• I hear that some of the early Android devices (the G1 for example) can no longer get upgraded to the latest versions of the OS (correct me if I'm wrong)
  
• The time will come (probably this year) when 1st gen iPhones can no longer be upgraded to the latest version of Apple's OS.

This illustrates the point nicely: other vendors typically support their hardware with the latest version of their OS for at least 18 month after their introduction. After that point, one might argue that the hardware becomes obsolescent and supporting dated devices has a clear cost for the manufacturer. 18 months also happens to be the typical network contract length these days so this value proposition makes sense from a mainstream consumer's perspective.

With the N900, Nokia's refusal to spell out clearly what will happen with Maemo 6 with it due under a year into the N900's life is a genuine issue for prospective buyers such as yourself.

I suspect this will hamper the device's sales potential, its attractiveness for ISVs (who are expected to produce these much needed apps) and eventually Nokia's credibility and possibly its future.

Shame because like many here, I like the device (I bought one after all) and would really like to see Maemo succeed as an open alternative to those constrained "smart phone" OS...