I've only been listening to Simon Mayo's Book Review Programme podcast for three weeks, so maybe this isn't a fair sample, but the authors whose books were reviewed, were as follows:
Week 1: Martin Davies and Joanna TrollopeAs well as Simon and the featured authors, there are normally three reviewers. Weeks 1 and 3 had one female reviewer. So that's 1 out of 6 books by female authors and 2 out of 9 female reviewers. Perhaps this week there will be two books by female writers and a panel of female reviewers...
Week 2: Nicolo Ammaniti and M R Hall
Week 3: Nick Brownlee and Stephen Leather