There have been a couple of updates to Text Messaging under iOS4. The first is you now get a character count when typing your text messages. This is on by default, however if yours isn’t working go check under Settings, Messages and select Character Count.
You will need to type a line of text before the character count kicks in.
But wait, there’s more! If one of your text messages fails, no longer are you left assuming it went. A red exclamation mark will pop up next to the unsuccessful text message. This is a fantastic feature for those who live or move between signal deadzones.