REST is obviously taking over the world of web services. However, there are several vendors still pushing out SOAP compliant APIs and providing services that are SOAP based. The reason for this is many-fold.
Atomicity and Transactions
Only SOAP, through WS-AtomicTransaction provides complete ACID in the web service world.
In addition to standard SSL support, SOAP provides WS-SEcurity options. These can be thought of as message level security (encrypting parts of the soap message), as opposed to transport level security (which SSL provides).
One might ask, why do we need message level encryption when the entire transit is encrypted at the network level? That’s just the point – SSL takes care of in-transit encryption – but the actual soap message is unencrypted. If, for instance, your web traffic is routed through a proxy server, the SOAP message is decrypted at the proxy – which means it passes into your network in plain text.
Advantages of REST
REST is also better performing (reads can be cached, for example) and scales easily. Amazon (and eBay) are primarily REST based.
For an enterprise grade SOA that requires both Transactionality (between successive message calls) and Security (message level security), SOAP is still more powerful than REST. If these advanced security and transactionality features are ‘optional’, you may be better off with RESTFul services.