I've been a full time indie iPhone developer for about 9 months. I've recently ported my 2nd highest selling iPhone app to Android. Here is a comparison for the first 2 weeks of sales. If other iOS developers are out there that are thinking of porting to android, I hope this may be of help.
To keep things fair I'm only comparing one version of my paid iphone app to its android equivalent (Fantasy Football Monster '11). This does not include any ad revenue, in app purchases or iPad sales.
Date Android iPhone
Aug 25, 2011 $177.67 $420
Aug 24, 2011 $261.30 $382
Aug 23, 2011 $386.68 $386
Aug 22, 2011 $447.26 $425
Aug 21, 2011 $422.18 $585
Aug 20, 2011 $280.06 $403
Aug 19, 2011 $211.09 $352
Aug 18, 2011 $194.37 $388
Aug 17, 2011 $357.39 $342
Aug 16, 2011 $463.99 $330
Aug 15, 2011 $384.55 $407
Aug 14, 2011 $376.20 $483
Aug 13, 2011 $263.34 $502
Aug 12, 2011 $209.00 $508
Total $4428.08 $5914
Per Day $316.29 $422.43
So, overall the android version of my app makes about 75% of its iPhone equivalent. This is significantly better than I expected.
One more data point. The android app is currently about 250ish overall top paid, and the iPhone version is 350ish. Take from that what you will.
Some quick observations about android from an iOS developer's perspective:
1) I think developing quality apps is easier on iOS. I'm actually a Java/.NET developer by profession so I should naturally be biased toward Android. But once you get past the initial learning curve, I think that Cocoa Touch APIs get you 90% of the way there, whereas Android APIs get you about 30% of the way there. That is to say, if you want a lot of the nice UI touches you're used to on the iphone, you'll have to spend much more effort getting there on Android. The main advantage I feel Android has is memory management, but the reference counting method that Objective-C uses is second nature once you are familiar with the fundamentals.
2) Android gives you REAL TIME sales analysis. This is pretty incredible. Yes you can somewhat simulate this on iPhone using 3rd party analytics, but being able to see the moment someone bought your app just brings my obsession with checking sales and stats to another level. You also get your daily reports much sooner (about 12:30AM PST as opposed to 5-6AM PST).
3) Android market screws up orders quite a bit. In fact, almost 20% of all orders are declined or cancelled due to some android market error. After checking forums, it seems like this is not unusual. Now, I don't know if this means I have 20% lost sales, but still disturbing nonetheless. In android's defense, apple actually never gives you this level of detail. To my knowledge, you don't know if users can't buy your app due to an app store error. But judging from the fact that we get e-mails about this issue every other day on android and I've never gotten a single e-mail about this in the past 15 months I've been on the app store is very telling. Google has GOT to fix this. Developers lose, customers lose, and google loses.
In conclusion, I feel like the Android Market has really come into its own. The common wisdom that android owners do not pay for apps is demonstrably false. They may not pay as much per user for apps as iPhone owners, but the enormous marketshare Android commands is just too much to ignore.
I'll try to address any questions or comments in a timely manner, but I'm currently in Europe so please forgive me I don't get to all of them. Thanks for reading.