The desktop environment used by Solaris in SXDE is GNOME 2.18.2 as unfortunately GNOME 2.20 just arrived a little too late. Making Solaris Express Developer 9/07 more desktop friendly is included support for Adobe's Flash 9 player, GStreamer 0.10 with codec support for MP3s and other popular formats, and RealPlayer GOLD. For those artisans, GIMP 2.3.16 is also included, which is extremely nice.
While SXDE 9/07 does include Sun Studio 12 with D-Light, also included is NetBeans 5.5. No development edition of NetBeans 6.0 is bundled in this release. For those that may have heard about DTrace before, D-Light is a Sun Studio plug-in that is essentially a GUI version of DTrace. D-Light offers a variety of options and capabilities and was demonstrated at JavaOne earlier this year.
If you are looking to dive into Solaris for the first time, Solaris Express Developer Edition 9/07 is an excellent candidate for now. We're on the brink of what should be an interesting couple of months as Project Indiana approaches the limelight. Share your Solaris experiences in the Phoronix Forums.