Have read this forum since diagnosis (Nov 2007). Fertility issues were one of the things that were important to me and my wife at that time, so thought i'd chip-in with our experiences as it might help.
I'm being treated at Hammersmith and consultants there indicated they were happy for us to try for children - I was on Imatinib 400mg. From my own reading, it implied that the exposure to the hydroxyurea which I took in the first few weeks had more potential to cause problems than the Imatinib. My consultant arranged for me to have an apppointment with the fertility doc at Hammersmith who indicated he knew of no problems with Imatinib where the father was taking it. He did say there was a risk fathering a child on any medication, and that as there was little/no data specifically on Imatinib, in his opinion this was unquantifiably small.
Everything went fine and we had a healthy son Oct 2009. We did get some additional monitoring (nuchal scan) on the NHS thanks to my consultant writing a letter.
Anyway, that's our experience - hope that helps. My last PCR was 0.2% - been a bit of a slow responder and have just increased to Imatinib 600mg , but almost at the magical 0.1!