I recently needed to set the email address that Access Requests from SharePoint 2010 go to for all sites in the Web Application. Since there is no way to do this in bulk within the interface, I found this blog post outlining a useful PowerScript commant that parses through each SPWeb and sets the Access Request email for all SPWebs that do not inherit from their parent SPWeb. I have posted it here in case someone else might find this useful:
$webapp = Get-SPWebApplication "http://WebAppToSendFrom"
foreach($site in $webapp.Sites)
foreach($web in $site.AllWebs)
Write-Host "Access Request Setting is inherted from parent."
$web.RequestAccessEmail = "EmailToSendRequest@To.com"