Google has announced that it will be merging its two payment options
into one with Google Checkout now becoming a part of Google Wallet.
Enabling user who are currently using Google Wallet to be able to make
purchases on Google Checkout enabled websites.
If you are a current user of Google Checkout you account
will automatically be merged by Google into Google Wallet the next time
you login or make a purchase.

Google has also stated that it will be making Google Wallet a payment method for purchasing applications
on the Android Market. All Google Checkout and Google Wallet users can
now access online purchase history and payment information at the Google Wallet website.
Source: Google |