Our SP2010 farm has Outbound Email config'd just fine in Client Admin. What I've not found though, is an explanation of just what we would get by configuring Inbound Email. Google tells me how to configure Inbound Email, but not why I should bother. I haven't come across anybody screaming about it not being enabled, so I ask the SP community here: What exactly does Inbound Email provide?
Inbound email allows lists to receive email. This allows a SharePoint list to be configured with its own email address. Incoming emails usually create new list items with the details of the email and body of the email. In addition the original email and attachments can be attached to the list item.
This is a good replacement for public folders in Exchange that receive email into a shared folder. You can create workflows, custom views, etc., on the lists that receive email to accomplish some business need.
Incoming email enables you to send emails that end up in document libraries or other lists. Most of my customers are using this to archive/attach mails belonging to a project or make them searchable.
"The incoming e-mail feature enables teams to store the e-mail that they send to other team members without opening the SharePoint site and uploading the content that was sent in e-mail. This is possible because most types of lists and libraries can be assigned a unique e-mail address."