Build a good app and people will buy it.
I've already bought a couple for my Nexus One, and they have proven incredibly useful, fun, and a joy to use. One is a time-tracker for professional time billing has paid for itself many times over. Another, a WiFi analyser has also come in handy numerous times. Oh, did Imention I've only owned the phone for a few days?
So yes, good apps will be purchased and those authors will make money.
To digress from the app development side of things for a moment there seems to be quite a few mud-slinging articles (on which there are no comments allowed) contains the following paragraph;
"My confidence in Apple rests on its comparative advantage in the user experience (UX) - it's still streets ahead of the rivals in ease of use. If you don't believe me, try a test with someone who has a new, rival touchscreen phone; invite them to change the wallpaper or the ringtone."
OK, I'll take that test. Out with my new Nexus One, touch the top button to turn it on, slide the unlock, touch and hold a blank spot on the existing wallpaper, up comes a menu, select "Wallpapers", select "Live Wallpapers", and then select the one I like. Boy, was that ever difficult... NOT.
OK, perhaps changing the rtingtone is difficult. Select Applications, select Settings, select Sound, select Ringtone, then select the sound you want to use. Nope, that too was a simple process too.