You must have missed the point on what drains the n900 (and milsestone) battery.
It's the 3g and given that the consumption will vary hugely from network to network and from baseband sw to baseband sw.

Here in italy, both n900 and milestone, were lasting in about 6 hours if used on vodafone network, but if used on three network the average last time was about one whole day.

Now both phones are doing better.

The difference is that n900 is doing slightly better, the milestone is doing hugely better.

Given that saying "my n900 last in 24+ hours" is simply pointless, you are on a different network, maybe just 7.2 or lower, I'm on speedyer network and this makes the difference.