PowerShell to assign Exchange 2010 Retention Policies based on AD group membership

In exchange 2003 we maintained a 6 month and 12 month purge policy that was applied based on group membership. I described that configuration here. I wanted to migrate our purge policies to the new 2010 Recipient policies. I needed to find the members of an AD group and assign a retention policy to their mailbox. Here is my script:

Get-ADGroupMember mailboxpurge-6m | foreach {
if ((get-mailbox $_.samaccountname).ServerName -eq "server01" -OR (get-mailbox $_.samaccountname).ServerName -eq "server02" )
{
write-host "User" + $_.samaccountname + "'s current policy is: " + (get-mailbox $_.samaccountname).RetentionPolicy
set-mailbox $_.samaccountname -RetentionPolicy 6MonthPurge
}
}