IBM have written an article on how to Choose an ESB topology to fit your business model some of the bits are pretty good, but its also like a project management method article that starts by pushing waterfall. The first item up is the Single Global Company model which provides effectively a single ESB even if its actual deployed federated.
What they really don't cover in any depth is the differing requirements of business objective and integration that the different ESB products attempt to solve. Its a decent article in the problems it raises, if it does make the mistake of assuming (beyond a very light governance section) that technology is the primary saviour. The solutions are really re-workings of traditional EAI solutions rather than looking objectively at Service Oriented problems. Picking on the brokered ESB pattern, where it is suggested that a broker is required to provide the bridge, it is liable to be simpler to manage if its done via policy on a source bus which chooses which service are made external across bus boundaries.
Its a good article in highlighting the problems and challenges that inherently happen because a single ESB is not a viable solution in any non-trivial organisation. But I'd argue that its more an EAI pattern article re-badged for ESB than a set of patterns aimed at business Service challenges, in paticular they don't stress use of policy and governance as a mechanism over older EAI approaches.