One February 19, 2013, 24 of the 27 EU member states (all but Bulgaria, Poland and Spain) signed the agreement that establishes Unified Patent Court (UPC) and unitary patent system. Italy changed its mind and joined, and Bulgaria is expected to budge and sign soon.
Requests for unitary patents may be filed from the later of January 1, 2014, or the date that 13 countries (which must include France, Germany, and the U.K.) have ratified it. Full press release from EPO can be found here.
Prosecution (application requirements, examination, etc.) before the EPO remains the same until the point the examiner decides to grant a patent. Once the new system goes into effect, applicants will have a choice of proceeding under the old county-by-county validation system or the unitary system. Unitary patents can save money up front because there are no translation costs (as you had with the national validation system) and you pay a single annuity for the unitary patent as opposed to each national annuity. But you do end up putting all your eggs in one, unitary basket, the validity of which will be determined by the UPC. So litigation-prone clients and attorneys may prefer the old system where you get multiple shots at the validity question.