I remember a senior British Conservative politician describing the Commonwealth of Nations as a 'comfortable old sweater'. It doesn't look flash, it doesn't serve too many useful purposes, but it keeps you warm and it feels good.
The Commonwealth of Nations was formed out of the old British Empire and is a group of nations who have a shared history, a shared language and similar political and legal systems. They get together once every four years for the Commonwealth Games, second only to the Olympics as an international, multi-sport event. They have a secretariat which oversees worthy activities such as the promotion of democracy and human reights in member nations, as well as charitable support from the rich members (UK, Canada, Australia, New Zealand, Singapore, Cyprus, Malta, South Africa) to the poorer members from Sub-Saharan Africa, Asia and the Carribean.
The Commonwealth of Nations survived the fall of empire because it redefined its aims, focussing on areas that would be of real benefit to its members. Curiously, it's popular, and even nations that have no British imperial history have joined (Mozambique) or want to join (Rwanda, Algeria, Yemen etc.).
Attention in Chisinau is focussed on another Commonwealth that was formed from the ashes of empire. This time its the Commonwealth of Independent States (CIS) and the empire in question was the Soviet Union. Unlike the Commonwealth of Nations, the CIS has not really found its 'raison d'etre', being viewed mainly as a symbolic device through which Russia can express its continuing hegemony over its former vassals. It's been basically incoherent, with very little to show for its 18 years of activity.
Many in Moldova (rightly) resent Russia's hegemony and seek Moldova's exit from the CIS. If, however, you look at things with a cool head, you will see that the CIS is basically harmless. Should it attempt to acquire a strategic / military / geopolitical dimension, then in any case Moldova would have to leave, due to its constitutional neutrality. Should it focus on reinforcing economic, sporting and cultural ties (following the example of the Commonwealth of Nations), then (a) being a member of the CIS won't conflict with EU entry and (b) it's probably a good thing for Moldova overall.
Remember that the nations to the east of Moldova aren't suddenly going to disappear of the face of the Earth the day Moldova joins the EU. She will still need to deal with them. Moreover she can benefit from the shared history and cultural heritage enjoyed (?!) as former Soviet republics and provinces of the old Tsarist empire. Furthermore, continued membership of the CIS will help sooth the nerves of Moldova's ethnic minorities, who have been whipped up into a frenzy by communist misinformation over the last few months.
Don't get me wrong. If push comes to shove and Moldova has to choose between the EU and the CIS, then it's a no-brainer which way she should turn. If, however, the CIS can morph into a 'comfortable old sweater', then there is no reason why Moldova shouldn't continue as a member.