Nokia (NOK) shares tumbled nearly 8% Monday as Nomura Holdings cut sales forecasts for the Lumia 900 smartphone. Current phones that run on Microsoft's (MSFT) operating system won't be able to upgrade to the new Windows 8 due to hardware limitations, Microsoft said June 20. The news could make Nokia's flagship phone obsolete as customers clamor to get the latest technology. However Microsoft did make it clear that current Windows phones would