My first impression is that there is no other technology like Cocoa EO so integrated to OS X, however I may be wrong. In the last two releases of the OS X, vers. 3 and 4 (better known as Panther and Tiger, resp.), two nice technologies had been included in the "free" DevTools: namely, Bindings and Core Data. Watching the big picture, these frameworks looks like an attempt from Apple to rediscover Enterprise Objects, but now fully integrated into Cocoa — like if they were porting EOF back from Java to Objective-C again. To this to become a reality, one piece is still missing: the connectivity to a RDBM (like Sybase, Oracle, MySQL...); in EO terms, EOAccess layer...
The question is now: is Apple including this missing piece into Leopard (OS X 10.5)? NDA aside, no one knows for sure. WWDC was held a few days ago and, at least in the public statement, there is no light that this will happen soon.
On the other hand, Web Objects has become a natural citizen of OS X since it was integrated to Tiger — into Xcode 2.2.x — and it includes a nice technology called Web services, which is based on SOAP. I have not tried yet, but it may be a possibility to code a "service provider/consumer framework" to emulate the Access layer... let us try that for the moment.
