Although I agree it does make sense for them to price the update low in order to gain:
1. Maximum sales
2. Maximum amount of devices that are returned to 'Apple-locked'
It is also famed to be a HUGE update. As i've said before, ok v2.0 has the App Store .. big whoop! ... business features? - i'm a general user, I don't need them ... No, Apple will have something more in v2.0, something big. Something CONSUMER FOCUSED. Something we ALL want, straight after the keynote, it's the way it works. Something like iChat (no video support obv), A photo editor, Enhanced maps.app, An apple developed game? - Who knows, but I know it will be there. There has to be SOMETHING which is going to make me say 'Ohh ... YES Pleasee ..' - So far, I haven't seen it in v2.0 - not during the March 6th event anyway.
This is why I think Steve will demo some features which he and Apple held back from WWDC because they weren't ready .. and then announce a price of around $20-25 for v2.0.
It could even be as high as $30 (but i'm guessing Jobs and the board members want to keep their HQ free of fire at the Cupertino campus).
R-Fly