When I try to download the newest snapshot from http://assets.minecraft.net/12w49a/minecraft.jar, nothing happens. Then I try to load http://assets.minecraft.net/12w49a, but all that shows up is an error message in XML:

<Error>
<Code>NoSuchKey</Code>
<Message>The specified key does not exist.</Message>
<Key>12w49a</Key>
<RequestId>5881DFBBB645E8CA</RequestId>
<HostId>
v6aecI0hl5aEllaHyDbDgMu9mDM+mjHr7DPZsz+wEkBIKLXP2c1SwOEZKY/Hl3YR
</HostId>
</Error>