I'm going from bad to worse.

After having lots of problems for getting working "brcmsmac" driver in this
system (see bug #664767) I finally surrender tried again with the closed source
driver (wl) but this driver is not even capable of associate to the AP. I'm
attaching two syslog excerpts:

wl.txt → when trying to associate the wireless card with AP using wl driver
rt8200 → when I test with a different wireless card using rt8200 driver

As you can see, the former fails while the latter works fine.