The wl wireless driver is from Broadcom, it contains a binary blob that makes the driver conform to the FCC regulations in the US. Sometime between 2.6.26 & 2.6.7 they changed a setting inside the blob called set_vlanmode. The end result is that when using the driver in its default state you can't ssh or telnet into another box.
Ben Collins first noticed this behavior and filed LP Bug #259816. Broadcom has since fixed the blob turning the set_vlanmode off. That kernel should hit the repositiories this week. In the mean time if you want to workaround it you can do the following.
# sudo iwpriv eth1 set_vlanmode 0
Make sure you change eth1 in the example above to whatever you wireless interface is on your box.
That will disable the vlan setting and ssh will work again.