"The 'please excuse any errors' is soooo obnoxious! It's not that difficult to type properly and then reread before sending, regardless of where you're sending it from! I have a love/hate relationship with the signature, however. I do sometimes like to know an email is coming from someone's iphone as opposed to knowing my friend is sitting at her desk at work." — skigurl
For more opinions (and to share one of your own!), keep reading.
"In my industry where I am in and out of the office quite a bit having 'Sent from my iPhone' is a little indicator that while I can answer emails and do a few things there are other things that I'm not capable of doing at this moment, but I wanted to acknowledge your email and let you know that I will work on it when I get back to the office." — Akasha
"I think the 'Sent from my' (iPhone, Blackberry etc.) sounds so pretentious even though it's defaulted by the system. But I do like a purposeful signature such as my fave: '[Content Disclaimer] Brevity is probably intended. Composed and transmitted from a mobile device.' I like to keep it short and sweet because I'm typing on a little keyboard and this sig works great!" — vssalazar
"Personally, I prefer them, but that is also because I'm never physically in the office and the signatures allow people to see how reachable I am. Obviously if you see the signature says that it's coming from my phone, I may not be very accessible. However, I only use these email signatures when it comes to work. For personal emails, I don't see why a signature is even required." — missiza