SOA efforts frequently enjoy early success creating relatively straightforward services that happen to have few side effects, perhaps related to processing a payment or creating a new account. At some point, they realize a need for a data service, for example one that wraps customer account information. The usual challenges are not so much SOA related, but the SOA effort hits a snag because there are multiple opinions in the business about the meaning of data elements (what is a customer, exactly?), and because there is very likely many years of ignoring or working around data quality problems that has to be addressed. In other words, the SOA project can't succeed without cleaning up the data quality and definition issues.
My best advice in such situations is to take it in steps - don't try to create the complete data service in one lump, but instead start with one specific need and expand from there. The other likely challenge is one that is common to early SOA efforts - you will need some practice at defining services well. In other words, you should plan on some rework of initial services as you get smarter after the first year or so.
This was first published in June 2008