We just received an email from Android Market Support letting us know that Google Checkout will be down for scheduled maintenance from 4:00 PM to 5:00 PM PDT today. During this outage, you will still be able to see paid apps in the Market, but you won't be able to buy anything. So... if you were planning on dropping hundreds of dollars in the Market during the aforementioned hours today, you should probably get started a bit early... or wait until later. Your call.
Here's a copy of the email that we got, just in case you're interested in seeing it verbatim.
We're writing to inform you about a planned service outage impacting Android Market that requires your attention.
On Wednesday, June 15th, Google Checkout will be unavailable from approximately 4 p.m. to 5 p.m. PDT due to planned system maintenance. During this time, you will be unable to sign in to your Merchant accounts (http://checkout.google.com) and transactions will not be processed. The Android Market Developer Console (http://market.android.com/publish/) will still be available.
During the outage, users will still be able to view paid applications on Android Market; however, any attempts at purchases will fail. No new orders will be created. After the maintenance has been completed, all normal activity will resume. No action is required on your part.
Thank you for your patience and understanding.
The Android Market Team