Although this is a good social example of intermixing, it still doesn't constitute a community. That can only take place when each of these peoples lives begins to impact upon each other. The 'pub' example is social gathering that may lead to a community, just as those who meet in chat rooms regularly may do the same. A community only eventuates when communication AND interaction takes place. Simple chat is not interaction.
Communication is at the heart of the construct of a community as is physical presence.
The Internet can not provide 'real time' physical presence. At best it can provide video imaging through Web cameras and audio to go with the video, or even independently of it. This is a big plus for a virtual community as it does provide every opportunity to see and interact with many different people around the world in a conference like setting on your monitor. But still, physical contact is not present. This does not mean to say that the benefits a community environment offers cannot be attained online.