Securent has a solution for fine-grained access control which integrates with Sun Access Manager. There is a webinar that highlights some of the features of both products and the integration points. The Q&A is worth listening to as the speakers outline some additional points that are not covered in the presentation. I'm somewhat puzzled by the need to use securent in conjunction with Sun AM. Securent may have better auditing capabilities but other than that the architecture is same (Policy Agent, Policy Server, Policy Store) and I'm not sure why customers would invest in 2 products, especially that Sun AM can probably fulfill most requirements. I do find some cool things in securent's solution , especially around auditing and operational management of policies. They seem to address all the hurdles in managing fine-grained policies for enterprise applications.
When I have some time I may evaluate the actual product to have a better idea.