Ill simply let the pricing do the talking and you can decide which you want to use

Amazon

https://payments.amazon.com/sdui/sdui/business?sn=devpricing/fpspricing

Bango

http://bango.com/products/payment/payment_network.aspx

looks similar at first glance but then factor in Bangos minimums

http://bango.com/products/payment/world.aspx

Is operator billing worth the extra to everyday end users than Amazon? thoughts welcome in the comments!

Interesting stats on Paypal:

on average more than $2,000 goes through PayPal every second of each day.

It has 75 million active accounts, and it’s available in 190 markets and 19 different currencies.

However whilst these stats seem impressive you can see where Paypal see room for their growth when compared with Visa and Mastercard  FT article on PayPal opening up

From a mobile perspective obviously obtaining payment on device is something that until fairly recently has always been difficult, recent initiatives such as payforit which can be enabled by providers such as Bango and WIN, have improved the situation, but still only allow primarily “point of download” business models, which is cumbersome for many digital content apps such as ebook providers.

Indeed in app payment is pretty much still a nightmare for a developer, even the commendable carriers that do have systems to integrate with from an application; which have achieved the sort of scale that Paypal would be envious of active subscribers in the 100s of millions those numbers, however assume the API interface is the same across a given carriers territories. Fragmentation aside these carrier based solutions often suffer from the problem that if the user suddenly switches to a WIFI network then the billing system breaks down. People consuming data rich applications, and therefore probably the ones they are willing to pay for are probably likely to move to WIFI enabled handsets. Moving to WIFI handsets is something Bango highlight in their recent press release.

Even without the WIFI issue one of the problems has been scaling payment systems, something that RIM (using Paypal Screenshot of Blackberry app world payment system) and Apple have done better than most.

Googles checkout for Android unfortunately suffers from a couple of irritating problems in that the currency is fixed, so as a end user if I purchase something from the store it could well cost me a couple dollars, however many UK banks will then charge a overseas transaction fee of a £1 and 3% or more (useful comparision of overseas transactions fees from UK banks here) , as a developer this  means you would have to present the user the item in a foreign currency, which is far from appealing! As the same developer looking to accept payment, scaling with each individual carrier is time consuming and difficult and becomes a project in itself and is in my mind one reason the advertising route for mobile applications has been so successful to date, because it achieves scale so much more easily.

So I am hoping that Paypal can provide the trusted partner that is needed in the mobile ecosystem to enable (preferably) micro payments from mobile websites and mobile applications whichever flavour they come in Android, Blackberry, iPhone, J2ME, Symbian or Windows mobile, as at the moment the only platform this is available for is iPhone with some restrictions on the inApp purchase side