The n900 will be the peak for some time to come,
remember how long it took to market -

The folk in India only just got it and it has been better part of a year
since first frothings. It will take quite some time for anything to appear.
Buy spare batteries, maybe even a backup unit
because nothing is on the horizon - and even if it was on the horizon
the racism-driven and bribery-politics approval policies around the globe only reluctantly
permit new-fangled power devices like the n900 through.

That said,
imagine all the ways just how bad the next device can fail, miserably.

1 - No ISO 8601 date-time format.
(You get your choice of jew-catholic-protestant-muslim-buddhist-Howling_at_the_moon date-time schemes)

2 They omitted the seconds display from the clock in the n900
Next version omits minutes as well, just shows lunar phase (see above)
Update - Wonko fixed this !

3 Cripple the software update process so that only people on approved networks can access repositories.
(right now anyone behind a firewall has no hope of downloading apps with the notably nice app manager
because there is no SSL access to the apps and the package descriptions are all for vanilla http)

4 Remote bricking. All they need to do is use that button once...
(On second thought maybe better buy two spare n900s....it may be longer than we imagine)
[ hackers with botnets will hold the management hostage - imagine being able to
remotely brick a million devices in a market with a single commit.
Would we refer to installing remote bricking as corporate suicide or what ? ]

5 Corporate, religious, and/or governmental settings lock-down
(peer-to-peer SIP does not work in the default Nokia implementation because they
wanted to lock you into having an account. No account - no communicate.)
They want to require accounts in every communications application - no freelance stuff allowed.
Thank some poor souls who fought the good fight that n900 has a linux kernel.
(You have noticed all the wailing for Android and M$ in the media?
It is as very disturbing to know just how strong the impetus is to
lock you out of your own property in favor of dumbed-down fingering.

Fingering in public should be embarrassing to the literate -
it basically says -
"Look at me -
- I am not only innumerate but functionally illiterate as well but -
- hey - I can use a smartphone."
[marketing prefers to use the term gesturing, but watching it whatever you label it is just as
entertaining as watching someone pick their nose at the dinner table.
Parents - do you let your teenagers Finger, in public ? ])

Let us fervently hope and inspire as best we can these folk to improve upon the magic of the n900.

That said, beware that trends of the past are the best prediction of the future.

If that holds true,
the screen on the next Nokia flagship should be 3inch or less.
See an optometrist for the immediate fix to that issue...