There is a bug in the 1.01 MultiPing that stops the use of $host in the alert email subject name. The design of the alert system specifies that you can customize the alert subject and use variables ($host, $date, etc). Unfortunately, this doesn't work correctly in the current release.

A temporary workaround is to create multiple instances of the alert and enter the target name explicitly in the subject line (the alert setup has a subject line entry box for you to do this), and then associate the correct name to each IP. It's a bit painful, but works.

We'll be issuing a bug fix for this in the very near future.