What is more important: more RAM or faster CPU?

IMO CPU, because starting & using MicroB (even w/o extensions) is simply too slow for fast usage. The NIT should IMO be a device you pull out of your pocket to look up something quickly. Some functionality is quick like RSSm weatherm or e-mail but there are some options you really need a browser for. For example: to look up when a train arrives, or a price check on a product while you're shopping.

It is also important to note that the competition is in usability and the hardware / price for money field. Tablets will become more popular, and there are already competitors & clones coming out too. Nokia will have to decide its position on the market, and the N900 is an ideal milestone to do so.

PS: I am interested in making an objective Wiki page about this subject with all the pros and cons outlined. The idea is to devide in 3 parts: 1) small changes (e.g. a bug or feature previously in a NIT) 2) big changes (ie. things Nokia would use in a marketing announcement) 3) research / expensive changes (like e.g. solar power, totally different hardware platform, and so on). What more should I keep in mind before I start?