The lastest version of BSIMM - Building Security in Maturity Model has just been released [27th September 2011].

When the BSIMM project started I was excited but apprehensive - the challenge to produce such a maturity model was enormous. With BSIMM3 we not only see the fruits of a huge amount of detailed work but the team behind it have proven that they can bring together lots of disparate firms with different ideas together under the BSIMM banner. The scientific foundation of BSIMM is its strength - the rigour behind the work is a joy to behold.

Check out the details here http://bsimm.com