I have just installed Ubuntu 13.04 on a nexus 7.
The steps were, in a terminal on the nexus:
$ apt-get install openssh-server # answer y
$ ifconfig wlan0 # to find nexus IP address
Then, on a computer in the same wireless network,
$ ssh loginname@ip-address
The authenticity of host '192.168.131.40 (192.168.131.40)' can't be established.
ECDSA key fingerprint is 54:22:d3:ea:2e:af:b2:87:23:74:1a:ce:f5:e5:e4:11.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.131.40' (ECDSA) to the list of known hosts.
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Welcome to Ubuntu Raring Ringtail (development branch) (GNU/Linux 3.1.10-8-nexus7 armv7l)
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