To text or not to text?

A discussion has been occurring in my life that I never thought would.

"when is it okay to text?"

And, it's truly a dilemma. I try not to text while having a conversation with someone in the room. PC is an exception, b/c sometimes he's in the room and well, he gets it.

For example, a lunch out recently at a fairly nice establishment netted me spying 2 couples texting while at the same table. They weren't talking to each other. I don't know if they were texting each other, but it seemed odd.

At knit night last night, two members texted each other within the group. While I thought this was incredibly rude, is it really? I consider whispering within a group rude.... but I was raised that you kept your thoughts to yourself and discussed them at a later time, if necessary. But, is it rude to text someone the equivalent of a whisper? I'm not sure society agrees with me, and I am quite all right with being wrong.

And, what about out with a friend? Is it okay to remove yourself (with or without telling your friend) from the conversation or activity, and text? Or tweet?

Does the relative silence of the texting activity remove the 'rudeness' factor?

Please, help the 'uninformed'. And, yes, I cast on for Girl Friday last night. Photos once I have something beyond ribbing.