Don't confuse the Linux work with the GA VC Server on Windows. Yes, that was released in 2007, butr work for the Linux port was not partof that effort. The Linux tech preview was started in 2007 (before that really) but was only realeased earlier this year. It had just been released when I presented on it at VMworld EMEA. I assure you, we are making progress. In the future, Linux releases will be syncronized with Windows releases, but I don't think I am yet at liberty to say what the first release is where that will occur.
We are working on a unfied strategy for the UI as well, but that is actually far more platform dependant thant hte Server piece is, and requires a larger set of technology changes.Just conbsider that the current GUI is built on .NET and you will get a sense of the effort required.
We are aware of the DB issues, and we are working on a better set of options. For my development, I started out with OracleXE in a separate VM. This is where I would advise you to start. In the future, we will be supporting Oracle and DB2 at a minimum. Beyond that, there is a lot of pressure for an embedded Database, just like you said. That is as much as I can really say at this time, but we hear you. I will leave you with this: the VC LInux project started because engineers at VMware recongized the need and quality of running VC on Linux, and only later was it accepted as a key piece of corporate strategy.
Bringing vCenter to Linux