I must say that the rendering speed is almost the same... as far as you don't scroll through a large page. In that case the Nexus One is *much* faster (maybe the extra ram comes into play?

Another difference is portrait mode: in the N1 is usable as the text "reduces" it's length to fit the page. That does not happen on the N900 (I know, the support for portrait mode is not official yet...)

I've been playing around with both devices and I will go for the N900