They need to borrow a page from Apple's book and build a SPARC-based "Sun mini" that's cool, desirable and cheap. It should also be the obvious choice for a desktop platform for anyone who wants do develop for Java, Solaris or whatever Sun thinks is strategic.
Getting CMT chips in the hands of maverick developers is vital if they want people to develop for them. Parallel stuff is seen as cool and sexy and their CMT SPARCs are built for it. I would buy a desktop Sun to "test the water", but I wouldn't do the same with a rackmount server. If they have rackmount servers going for USD 2700, they sure can do desktops for about USD 1000. If they can make Ruby or Python do great threading with them, all the better as I have no real desire to program in Java.
Back in the OpenWindows or CDE days, Solaris wasn't a terribly nice desktop environment but today, with Gnome, it is every bit as good as, say, Ubuntu. The right people should start seeing the Sun logo more and the huge userland Unix-like OSs have is key.
And, while they are at it, the JAVA ticker was a stupid idea. Sun is, and should be perceived as much more than that. SUNW was not a brilliant one (as workstations were no longer relevant)