Getting Solaris to run on ESX is a little bit tricky but possible. In thread
http://www.vmware.com/community/thread.jspa?threadID=25995&start=0&tstart=0 I posted some step by step instructions. You will need VMware Workstation and a subscription for Solaris updates from Sun (to get mpt version 1.26) to follow these instructions. Be sure to complete reading to the end of the thread, as there are some additional paramaters needed to not only get it to run, but also get it stable!
In the meantime, I made patches also for the SCSI driver of the Solaris 10 base distribution (mpt version 1.24). Patches for both versions (1.24 and 1.26) can be found at
http://wotho.ethz.ch/ESX_solaris/Solaris_10_patches_for_VMware_ESX.tar. The installation process for the 1.24 version is the same as mentioned in the above thread, except that there is no need for updating Solaris after installing from the distribution media and correspondingly no need for patching /platform/i86pc/kernel/unix.
I also made a modified Solaris 10 Installation DVD, which can be installed directly on ESX, without the diversion to VMware Workstation. Installation from this DVD automatically sets the correct parameters to get a stable Solaris VM. If you like to try it, I can make the iso image available to you.
If you got it to run: On
http://wotho.ethz.ch/ESX_solaris/vmware-tools-lxrun.tar you find some files needed, if you want to get vmware-guestd to run. See the README file included for instructions. Of course, I can provide a directly installable iso image for this also. Functionality is of course only delivering of heartbeats and configuration info to the ESX server and executing poweroff and reboot commands if requested by the server. No vmware-toolbox, no hgfs, no vmmemctl and no vmxnet...