This is from the Chair of the DS434 Plain Packaging WTO panel:
On 28 May 2015, the Panel received a request from Ukraine to suspend the proceedings in Australia – Certain Measures concerning Trademarks and other Plain Packaging Requirements Applicable to Tobacco Products and Packaging (WT/DS434) pursuant to Article 12.12 of the Understanding on Rules and Procedures Governing the Settlement of Disputes (DSU). In a letter dated 29 May 2015, Australia indicated that it "supports the request by Ukraine to suspend proceedings, on the basis that, as Ukraine has said in its letter, the suspension will be 'with a view to finding a mutually agreed solution'".
Article 12.12 of the DSU provides that the Panel may suspend its work at any time at the request of the complaining party for a period not exceeding 12 months. This provision also indicates that if the work of the Panel has been suspended for more than 12 months, the authority for establishment of the Panel shall lapse.
The Panel hereby informs the Dispute Settlement Body of its decision of 29 May 2015 to grant Ukraine's request and suspend its work and requests that this communication be circulated to Members.
That's all I know. More details as they emerge.