I’ve just seen an interesting piece of software called MyKidisSafe.com which is basically a mobile phone application aimed at Parents that allows them to monitor and restrict use of their kid’s phones.
You can set times when the phone can and can’t be used e.g. in class times, monitor MMS, limit SMS usage, to name but a few functions. In terms of SMS an interesting feature looks for 1500 objectionable words in text messages, when an objectionable word is found parents are notified. Additionally, if your phone has GPS the software can restrict mobile phone use while driving. Big Mother is watching you!