MySQL documentation has now been made available in ePub format (fetch the MySQL Cluster versions from http://dev.mysql.com/doc/index-cluster.html ). This format is intended for various book readers.
I’ve tried it on 2 iPhone applications; Apple’s iBooks and the iPhone version of Stanza. The documents render well in both applications but as with most reference books you get the best results if you reduce the font size so that you get more on the screen at once.
With both applications, you can add the books through iTunes but Stanza also has the advantage that if you browse to the document in Opera on the iPhone then it gives you the option of opening it in Stanza – cutting out the need to use iTunes. I also prefer the rendering in Stanza. The only problems I’ve come across with Stanza is that you have to add the cover images yourself (if you care) – not a huge problem.