Is there anything like NVELO Dataplex (hybrid SSD/HDD software) for OS X? I'm interested in upgrading my old MacBook to using an SSD and moving the data drive to where the DVD drive is using an optibay.

Often SSDs come with a licence for NVELO Dataplex software (which is windows only). This software is basically a windows driver that keeps track of commonly used files and moves then to the SSD, thereby giving you a hybrid SSD.

Is there anything like NVELO Dataplex for OS X or should I just put OS X and applications on the SSD, and put home folders on the HDD using symbolic links?
This is an old question, but for the benefit of anyone who comes across it: Apple introduced this capability under the name Fusion Drive in late 2012. Officially you can only get a Fusion Drive as a build-to-order option on a new Mac, but many people have reported success with configuring their own using the diskutil Terminal command in OS X 10.8.2 or later.