Here's how I do it. I set an email address with a sekrit token in my blog's preferences, and then put something in a .qmail file on my mailhost:
| sed '1,/^$/d' |tr \\012\\015 ' ' | env NEWSENDER=me@mailhost mail -s "from my cell phone" firstname.lastname@example.org
I send email to the address on my mailhost, it strips away the header, converts newlines to spaces, and forwards it to my posting address on blogger.com. I can't directly use my cell provider's SMS-to-email gateway to email email@example.com because blogger complained about my mail being in message/rfc822 format (that's a bug?).