In recent years several Eastern European countries have introduced new internet gambling laws but the actual take up of licences and launch of operations has been very slow.
This is how the indivdual countries have fared:

Croatia – allowed Internet gambling for land based operators from 1 January 2010 – 4 operators – for the largest operator over 40% of betting handle coming from the Internet 

Serbia – allowed Internet gambling from 31 December 2011 – only the National Lottery with Sportingbet launched online so far 
Montenegro – allowed online gambling with 2004 law – no operators yet – law being revised 
Macedonia – allowed online gambling with 2011 law – no operators yet 
Republika Srpska (part of Bosnia and Herzegovina): allowed Internet gambling with 2008 law – one operator, also targets other markets 
Bulgaria – allowed online gambling from 1 July 2012 – no operators yet 
Romania – allowed online gambling from December 2010 – no operators yet. 
With the exception of Croatia, few of the countries above have developed a credible e-gaming market under the new laws. What are the reasons for this? First of all, most laws are made to protect incumbent operators and sometimes even require a land based licence with a certain number of betting/lottery shops or gaming halls. These laws were even adopted in some EU member states, despite the critical opinion from the European Commission. Even if they do not require a land based licence, annual fees are set at a prohibitive level. Also, most Eastern European markets are very small and so not of great interest to larger offshore operators, especially if the tax rate is not viable. The economic crisis has also significantly decreased investment. 
The enforcability of the ban for unlicensed companies remains very low, which means that many .com operators still target these markets from offshore. They often advertise widely, even though it is forbidden in theory.
In order to better protect their own citizens and secure revenues for the state, Eastern European countries should adopt less restrictive online gambling policies, open the doors to foreign operators and consider deals that would allow pooling of liquidity, especially for poker. As the Croatian example shows, online gambling in Eastern Europe can work, at least for larger operators. With lower licence fees, it would be even more competitive. And then it is up to the operators to draw clients with their innovative products and high payouts.