Reference: List of New and Revised Entries, Oxford English Dictionary (June 2013 Update)

The complete list can be accessed here.
New entries include:

• Geekery
• Live Blog
• Mani-pedi
• Showrunner
• Veepstakes

Also, in this OER Update

From the OED Blog

Those following @OED’s Twitter feed will be pleased to know that our entries for follow (verb), follower (noun), and tweet (noun and verb) have been expanded to include the social media senses, usage of which has exploded in the past six years. There has been, for example, a threefold increase in instances of the word tweet between 2006 and 2007 (when Twitter began), and by 2012, this had increased to 50 times.

More about the June 2013 update in this blog post and John Simpson’s commentary***. Simpson is OED’s Chief Editor.
Regarding the word tweet Simpson writes:

The noun and verb tweet (in the social-networking sense) has just been added to the OED. This breaks at least one OED rule, namely that a new word needs to be current for ten years before consideration for inclusion. But it seems to be catching on.

*** Note mention of the word e-reader.

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