I also suggest Beginning Android book.
As you have already chose Android, I like to add few words to above discussions which can be helpful to others. Exactly six months ago, I had same question in mind and I chose iOS. I am a Mac user [hackintosh
] and I like iOS and felt like developing apps for it. I chose it because I liked it
My friend who is also a developer told me, no. of android devices in India, price range below 15k is very much compared to above. And no. of people who buy your apps in android are more in those who own 15k+ device. Hence, your app is highly unlikely to be paid. [I don't know how much true this statement is & also it was told to me 6 months ago.]
I can tell difference between iOS & Android app dev. No. of Android users are growing everyday, so if you develop an free app [filled with ads], you can earn money & also name. Once you acquire good name, then you can sell your apps. Android is not that bad at all. For iOS app development, you need Mac, that means one have to invest again. For students / newbies / freelancers this could be tough. Initial Mac OS device [Mac Mini] costs 30k+ approx. Next, you have to pay $99 to evil Apple every year. As for Android it's just one time registration of just $25. [correct me if I am wrong] And also Android SDK tools can be easily run in Windows. Suppose if shit happens & if u need technical assistance, then evil Apple will charge 99$ per session. [or two sessions I guess]. But where as in Android, which is an Open Source, a lot people will be ready to help you at very less costs. [And yeah, there are forums for both platforms]. Advantage with iOS is less fragmentation. But no. of Android devices are very much & you have work more to make sure that it works in many devices. Another problem with iOS is getting your app approved. Apple tests each & every app before adding to appstore. It may take 2 days or max 10 days. In android, your app almost appears instantly.
Now, if anyone is unaware & confused which one to go, here are my suggestions :
1. Chose which one you like & what makes you happy to work on. Either it may iOS or Symbian, if it can keep you happy & then forget money
2. If you already know Java, then Android will be easier. For iOS you have to learn Objective C & Cocoa Touch [which are not that hard]
3. Among all, I would suggest Nokia, either Win Mobile or QT+. QT+ reasons have been already stated by Dhruv & Darkstar to which I agree completely. Nokia's dev support is top notch & tools are really good & can be run in Windows. As for windows mobile which require VB, C# [correct me if I am wrong] which are dead easy to learn. Once Nokia releases their Windows series there will be huge demand for apps & you will easily earn name as stated by paul.
Hope this helps