What would you do if you start an IT journey to SOA? You buy a service bus first? Or you introduce service governance first?
Buying a service bus is easy and quick. And you can probably boast about the fact that you are "doing SOA." But without governance, your bus will eventually cost a lot of money in maintenance, and is at risk of quickly becoming a legacy system.
Introducing SOA governance is generally more difficult, because it touches the organization and its business processes itself. But if you govern services properly, you don't need a bus per se to come to a SOA. The bus is then a tool which will facilitate the governance.
So, SOA governance should be taken seriously from day one of your journey to SOA, and it is probably more important than having a service bus. So maybe using a Service Repository is more important than using a Service Bus?