The new RESTful provisioning standard, SCIM, is being discussed a lot recently in comparison to SPML. Dave Kearns has some interesting thoughts here.
While Dave makes some good points I think he is entirely missing the reason the SPML was never accepted. SPML never gained traction because enterprises and application vendors never adopted it. It didn’t matter whether the provisioning vendors supported it or not, and it won’t matter if provisioning vendors adopt SCIM or ignore it.
Enterprises and service providers drive adoption. The ISVs will meet their needs. If SPML or SCIM is demanded, it will be provided. That demand never materialized for SPML, partly because the provisioning vendors already had non-standard solutions for the problems SPML was intended to solve.
Will this demand materialize for SCIM? Time will tell the tale of these two standards.