In the UK, "R v. ....." (usually v. rather than vs. for "versus") is how legal cases are described; the "R" stands for "Regina" (or "Rex" when the monarch is male) and means the state prosecuting authority. So "R vs. Yourself" means the case which in which the state is prosecuting you for some offence.

The government and its agencies act in the name of the monarch in the UK.

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Note added at 19 mins (2011-06-12 23:23:51 GMT)
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In principle, it means the State itself, as personified by the Queen. In practice, prosecutions are conducted in the UK by the Crown Prosecution Service (note the word "Crown"!). See this article for further details:
http://en.wikipedia.org/wiki/Crown_Prosecution_Service

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Note added at 20 mins (2011-06-12 23:25:18 GMT)
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(Needless to say, the Queen herself takes no part in criminal prosecutions.)

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Note added at 1 hr (2011-06-13 00:31:21 GMT)
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Strictly speaking, the Crown Prosecution Service does not operate in the whole of the UK but only in England and Wales. The equivalent agenciy in Scotland is the Crown Office (again the royal title) and in Northern Island it is the Public Prosecution Service.

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Note added at 10 hrs (2011-06-13 09:52:41 GMT)
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Oh dear, spelling mistakes in the last note: "agency" and "Ireland", not "agenciy" and "Island".