Fairly easy to set up with only a few wrinkles. The standard 6.x-1.10 generated a lot of error messages byt the "dev" module - mailhandler-6.x-1.x-dev - worked like a champ. Getting the gmail mailbox to worked took the usual Google Mail tricks: Pop3, domain - pop.gmail.com, port 995, the username required the domain suffix and the "Extra command" is "/ssl/novalidate-cert".
FCKEditor was messing with "Default commands". Changing "Visibility Settings" - Paths to exclude/include - in admin/settings/fckeditor/editg by adding "admin/content/mailhandler/edit/1" seems to fix that. The default commands I am using at the moment are:
Security concerns still lurk but I will cross that bridge when I come to it.
I did not do anything special for SMS but an email message from my Tracfone worked after changing the email address of an authorized user to the "from address:" of my phone.
Twitter and Facebook may be next. Our home page http://ls.net is not all that sacred and it will be fun to see what our users come up with.