Teaching English in Central & Eastern Europe
The potential job market for teaching English in Central and Eastern Europe is the same as in Western Europe. While there are still lots of teaching jobs available, the inclusion of East European countries into the EU means that native English speaking Brits definitely have an advantage to getting the jobs since they generally don't require a visa.
But assuming you have dealt with the visa issue, it is usually easier to find teaching work in Eastern and Central Europe.
Generally no credentials are needed, although of course some experience is useful. If you do get a TESL certification, the CELTA is still one of the more widely recognized.
Overall, the best time to go to Eastern Europe and look for a job is later in the summer in order to find work for the school term that begins in late August or September.
Teaching English In the Czech & Slovak Republics
If you are teaching in these countries you are typically going to be working in the private sector as there are many more jobs available in small language schools than in large public institutions. The best time to look for work is in August to early September as this is when classes are just starting up again and all the schools will be hiring, typically for 10 month contracts.
A decent wage in Prague at a language school is 15,000 ck/month with accommodations included, or 20,000-25,000 ck/month without accommodations. Unlike a lot of the Western European countries, you can still make a decent living teaching English here.
Teaching English In Hungary
Hungary is the one East European country where your credentials will still be more important than your North American accent or your experience. Typically the wages are a little lower in Hungary, between 2-8 euros/hour, and most English teachers supplement their income from a language school with some private tutoring.
Teaching English In Poland
North American English teachers are in high demand in Poland, mostly because the country has typically not been the first choice of location for most would be teachers. Of course, experience and some accreditation will get you higher pay, but they are not necessary to find yourself a job in this country.
If you do have a CELTA, you can expect something along the lines of 2,000-3,000 zl/month for wages. If you want to freelance, the going rate is between 50-60 zl/hour.
The above is just a very brief summary of the extremely in depth set of articles in JobMonkey's Teaching English in Eastern Europe. The section provides an in depth look at the types of teaching jobs available in each country as well as tons of useful links for finding those teaching jobs.