An amendement regarding articles 29 and 30 of the DTC between Greece and Canada that was signed in Athens on 29 June 2009 (Law 3824/2010) and entered into force on 16 December 2010 was agreed after formal exchange of verbal notes between the parties. 
According to the amendment, the convention applies on income derived or capital owned on or after the first of January of the next following calendar year.
The exchange of the verbal notes confirming the amendment was adopted by the Greek Parliament by Law 4035/2011, published in the OJ 270A' on 31 December 2011.

The Protocol between the Hellenic Republic and the Swiss Confederation amending the Convention between the two for the avoidance of double taxation with respect to taxes on income and the protocol, signed at Berne on 16th June 1983 was ratified by the Greek Parliament by Law 4034/2011 (published in the Official Gazette A' 269/31-12-2011). 
The Protocol will entry into force according to the provisions of Article VIII fo the Protocol.  

The amendment of the DTC between Greece and Switzerland that was signed in Bern on 4 November 2010 is now submitted to the Greek Parliament for approval. 
For details on the content of the agreement and the relevant text please refer to our previous post on the matter:
The 2010 Protocol Amending the 1983 Greece-Switzerland DTC

On 4 November 2010 Greece and Switzerland signed a revised double taxation agreement in the area of taxes on income and capital. 
The Protocol contains provisions on the exchange of information which are in accordance with the OECD standards. In addition, the protocol specifies, amongst other things, that the dividend payments to occupational benefits schemes and public bodies will be exempt from withholding tax. 
Moreover, the rate of the tax that the source state is entitled to levy on interest payments has been lowered from 10% to 7%. 
Last but not least an arbitration clause has also been adopted, which is expected to contribute to the definitive avoidance of double taxation. 

The Protocol is currently not in force; it will enter into force after the necessary procedures in both countries have been completed. 

Source: The Federal Authorities of the Swiss Confederation (www.admin.ch) - you can see the relevant announcement here. 

The Ministry of Finance has issued a circular (pol. 1024/2011) providing guidance on the interpretation and application of Article 12 of the Double Tax Convention between Greece and Finland, on the tax treatment of royalties.

By Circular 1141/23-6-2011 the Ministry of Finance provides guidance for the application of the new regime on the taxation of dividends distributed by Greek companies, in respect to recipients that reside in a state with which Greece has signed a Convention for the Avoidance of Double Taxation on Income and on capital. The withholdong tax rates provided in the DTCs are in general lower than the current withholding tax rate on dividend payments enacted by Law 3943/2011 (21% for distributions that take place in 2011; 25% for distributions that take place from 2012 on). 

Conference: "TAX TREATY CASE LAW AROUND THE GLOBE", Vienna, 19-21 May 2011. 
My presentation concerns a 2010 decision of the Greek Supreme Administrative Court dealing with the interpretation of the Business Profits article of the Greece-Germany DTC.
Invitation and programme of the Conference