I'm en:user:David Gerard. I'm here to help with the documentation, mostly so I can use it myself (a sysadmin frequently tasked with setting up MW) better. If you want to get in touch with me, go to my English Wikipedia home page.
I release all my contributions to this wiki as Public Domain or equivalent.
Doing this for a living 
We just set up two RHEL5 VMs (intranet staging and live) and I've been having a (fail)whale of a time setting up Semantic MediaWiki for the in-house ontology geeks. Semantic Bundle is the only sensible way. I've also been gaining tremendous experience in PHP errors and compiling libxml2 2.7.7 and PHP 5.3.2 from source just to get an up to date libphp5.so.
MediaWiki on Ubuntu 10.04 is a little better. I'm using MW tarballs with distro supporting software. See Debian/Ubuntu for future hopes.
Use Leengux, not Solaris. Please. I worry about you. 
Expect the Solaris instructions here to improve. I can summarise my work documentation of MW on Solaris as "You really don't want to do this", and suggest you just use a Linux distro with a decent repository instead. CentOS 4.5 is surprisingly not-bad if you get a buttload of stuff from CentosPlus. On RHEL5, hit the IUS Community Project.
If you use Ubuntu or Debian, install the mediawiki package to get the prerequisites, then remove it and use MW from the tarball. (Until the distro offers 1.19.)
I expect using http://opencsw.org - a Linux-style dependency-resolving repository for Solaris, particularly Solaris 10 - would make life way easier, if all you have is a hammer. The work wiki is actually running on a Solaris 10 box, though thankfully I didn't do the original installation. I shudder to think what buckets of rubbish the original sysadmin had to install. By hand from sunfreeware.
One thing I'm doing on mediawiki.org is to create redirects and pages that just suggest other pages. This is so that typing a word into the "search" box will give a useful result. Again, my motivations are helpful selfishness, i.e. if it'd be more useful for me it'd be more useful for others. Let me know if I do something that appears unhelpful.