bit of an odd question about getting published

My trip home (to my parents' house) always involves catching up on mail.
This time I received some very interesting letters from a decent sized publishing house: one of their editors happened upon a copy of my thesis and they really want me to turn it into a book for them (they wrote to me in May, then they wrote to me more recently to make sure I had received the letter in May and attached another copy of the May letter for good measure).

Anyway, how much of a hastle is it to convert a thesis into a book? I think mine is pretty readable anyway but I have to translate some parts of it and do a bit of editing before I'm satisfied, God knows if the editors would be happy with that.

More to the point, how much of a hastle is writing for a publisher?

I figure some of you guys will have experience of this.