" This is backed by what the Executive Vice President of Nokia, Anssi Vanjoki, had to say at yesterday’s launch event. Vanjoki pointed out that “in later dates we will also be increasing the number of support for this [sic] and certainly moving forward it will also support Maemo”
To me that quote just reads as Ovi Maps will be coming to Maemo, not a specific version of it. I'm disappointed that Ovi Maps on the N900 isn't as good as the version on Symbian-based Nokias, but you need a better source than that to prove Nokia actually promised voice navigation for the N900.