Yammer is hiring.   Both server side (Scala, Java, Ruby) front end  (JS),  and especially mobile clients (Android/iPhone/Blackberry).
<a href="https://www.yammer.com/jobs" >https://www.yammer.com/jobs</a>
It is great company, with a really fun and awesome environment.
shoot an email at ardit33[at_gmail_com]
Ask HN: Who is Hiring? (April 2011)