Nevertheless, I downloaded the DVD image and Live Upgraded my SXCE build 114. Everything went fine with no package installation errors and very little cleanup.
When I booted build 115 I noticed a renewed Volume Control User Interface and experienced a blocking problem: Input Methods weren't working anymore. They just didn't work.
A search on Google was fruitless so I posted a message on the i18n discussion mailing list at OpenSolaris.org and a Sun Engineer gave me a quick response: it's a bug introduced in build 115 and fixed in build 117 (http://defect.opensolaris.org/bz/show_bug.cgi?id=9109).
The workaround is very simple:
# touch /usr/lib/gtk-2.0/2.10.0/immodules/im-iiim.soand then just logout and login.
# svcadm restart desktop-cache/input-method-cache