Do you think that assuming an online persona encourages people to play with the identity they present online.

Yes!!! I think that the availability of numerous websites of differing styles allow people to not only express their true self but also perhaps the self they'd like to be or want others to think they are. For example on Facebook, you have the choice of who you add as your friends and you also have the option to change your everyday status of who your feeling or what you doing.
However also websites such Gaydar and similar specifically designed websites allow people that would not normally express their true self in real life in worry that they may be discriminated against, can communicate and express themselves more freely and prehaps with this take more risks than they would do in real life.

Lister refers to similar topics such as the expression of self 'social networks and peer to peer network sharing' and one of his most important points of how the internet "breaks the connection between outward expression of identity and physical body"