Shazam for Windows Phone 7 has been available for a while, and the music recognition company has just released a new version for Windows Phone 8.
It seems however there may have been a bug in the last version for Windows Phone 7 or possibly some backend change, as the company has just released a new version for Windows Phone 7, and the changelog for version 2.3.4 only says:
We recommend that you install this update as soon as possible so that your history is saved tags in future versions
If that functionality is important for you find the update in the Windows Phone Store here.
Via WindowsPhoneApps.es.