Me and my hubby have discussed doing something similar but in the form of a blog prison diary. I have many letters from my husband that would make interesting reading for many. A lot of his letters discuss prison life, how he's treated and the regime and so forth. There is a mixture of a few positives and a lot of negatives lol!
When someone has been in prison for quite some time, letters do contain prison politics. My hubby rings me every day so we talk about 'my life' when he rings. His life inside doesn't change so he hasn't really got much general chit chat to write about apart from the prison's goings on. I know how to set a blog/website up and I am seriously going to give it a whirl!