Well before you say this Nokia forum how could it be unbiased well before I was set on a Nokia n900 I desperately wanted Palm Pre man that thing looked so cool but as time passed and it never got onto T-Mobile and problem after problem occurred. So where do I begin.
Hardware
Well both devices the Nokia n900 feel well built the Original Pre felt kinda cheep but now the Pre plus feels a lot better than than the original. The n900 feels much better built than the Pre Plus. The Pre Plus packs in 16gb of storage with no expansion slot. The n900 comes 32gb of storage on top of that with an expansion slot. The overall design of the Palm Pre Plus is very elegant and very nice. I would say the design of the n900 is very bulky but elegant still nice too look at but the extra bulk doesn't help. Keyboard while the keyboard on the Palm Pre Plus is improved from the original it still very tiny and difficult to use. While the layout on the n900 isn't the best it certainly is way better than the Palm Pre Plus' keyboard and the buttons press better. So hardware the n900 certainly wins. So lets go to software.
Software
After seeing both oses demoed and playing aroud with both of them both have operating systems that feel like something that is much more than a smartphone. I would call both devices "mobile computers". So in my opinion the WebOs feeling easy to use and feeling like it puts you in control makes it win in my opinion. Also WebOs has a few more apps and has alot good games. so WebOs beats Maemo by a slight edge here.
Openness and Hacker/Homebrew Friendliness
While the Pre plus is very hacker friendly and it is super easy to patch a WebOs device to allow homebrew. Sure you have to patch a Palm Pre/Pre plus to do that but Palm has shown no intentions to stop the homebrew scene on WebOs. Now Maemo ready to hack right out the box it even includes a command line just type Sudo gainroot your mostly done there is other stuff you can do with both devices. There are some very cool themes for both devices. Many cool homebrew apps for both devices. So the Nokia n900 is king when it comes to hacking. However the Palm Pre is very good for hacking but the Nokia n900 wins this round.
Pricing and Availability
The Palm Pre plus wind being as it is available on more carriers including cdma carriers like Sprint or Verizon. The Pre Plus is available on gsm carriers like at&t or as unlocked gsm. Now as unlocked phone you will find the Pre for 600-700 bucks ouch. The Nokia n900 unlocked is 400-500 so way cheaper there. The Palm Pre/Pre Plus being available on multiple carriers subsidized and also available unlocked. The Palm Pre/Pre Plus Certainly Wins here.
Multitasking
Considered a killer feature of both devices and executed well on both devices. In theory both devices could handle a lot of apps at once. The Nokia n900 could way more apps thanks to the faster processor and swap file. Video of Palm Pre running 22 apps at once beautifully http://www.youtube.com/watch?v=BsIEiDOBDDQ.
Nokia n900 can run up to 30 apps at once http://www.youtube.com/watch?v=7emvUBpEkbU. So the n900 wins because it can run more at once. The Pre wins because it has a better interface for multitasking that lets you preview. So te n900 could be a winner here the Pre Plus could also be a winner here.
Web Browsing an Multimedia
The n900 and the Pre Plus handle both of these things very well. The Palm Pre Plus and Nokia n900 both have excellent browsers with flash the n900 has a landscape only browser while the Pre Plus is mostly portrait only. So I would say it is a tie here. As for multimedia the Nokia n900 supports more formats and has 32gb of storage with expansion the addition of a larger higher resolution screen makes it win this one.
So concluding I like both devices very much. I think both devices are way better and more advanced than any Android, Blackberry or iPhone. So concluding both are excellent "Mobile Computers" I like the Pre Plus because it has better os and I like the Nokia n900 more because it has much better hardware.