As a developer of 15 years who has moved into a pen-test role, I can say that yes there are many transferable skills, some of which will put you at and advantage to testers who came from a pure security background.
Firstly and foremostly you understand the developer mindset, this means that you probably understand why a developer chose a particular solution, and understand some of their thought processes. As a developer you have a knowledge of their 'language' how they think and talk, and as such you should be able to communicate any security findings and recommendations in a manner that a developer can understand.
Secondly you probably have a much better programming base than many pen-testers, this will come in very useful for developing tools and apps to help out (really I've seen some of the hacked together tools, it's a wonder that they work at all ;)
Code Review... This is an obvious big winner, you just need to start looking for insecure patterns and insecure language idioms.
Your understanding of software development practices (agile, waterfall etc), can be quickly augmented with learning about BSIMM, SAMM, and SDL
Depending on your developer background you may have a good understanding of OS/networking innards. I spent some time in the networking/OS world, which I found useful to inform other developers what the computer was really doing with their code. Likewise if you have spent your time in the Web world, that's where your focus will likely be.
It's worth noting that you may feel that there are vast areas of knowledge that you are lacking, but there are no pen-testers who know it all. You will bring your own knowledge and skills, and as long as you are prepared to learn and teach, it will be a very rewarding career move. It also has the advantage of making your really hire-able in two fields.