It seems like you cannot use arguments for `URxvt*urlLauncher` so *if* you wan't to use pass arguments to uzbl you'll need to create a little wrapper script. This is not needed unless you want to do something fancy (such as load config from non-default location, set verbose/name/.. arguments etc) urxvt-to-uzbl.sh:
#!/bin/sh uzbl --uri "$@" &
make sure it's executable and in your path (or specify absolute path) and configure urxvt like this:
URxvt.perl-ext-common: default,matcher URxvt*urlLauncher: urxvt-to-uzbl.sh URxvt.colorUL: #86a2be
If you just want to start uzbl and let it use your default config, just put 'uzbl' there. You should now be able to see hilighted links, middle click them (this can be configured) to open them in uzbl.