A team of us have been researching the implications of SaaS on ISVs, Hosters, Enterprise customers and Microsoft for a few months. 

On Wednesday 22nd November, Juergen Pfiefer and I delivered the Greek Architect forum on SaaS. Its the first time I've presented my thoughts on the SaaS Implications for Enterprise Infrastructures; the feedback I got re-enforced my findings;

• LoB SaaS applications cannot be viewed like islands or treated as outsourced applications, or your infrastructure will quickly fragment, the user experience will drop and costs will increase. 
• Integration should be considered in four areas;

1. Identity
2. Operations
3. Data
4. Security

Enterprises who've not negotiated SLAs in the past will face a learning curve; those who have experience with outsourcing will be able to re-use their skills around contract negotiation and creation will be better positioned.

I welcome feedback either by email kevin.sangwell at microsoft com or via comments on this blog.