You joined 9 months ago and you still don't know if you can play online?!
Well anyway... ESF is an online multiplayer game, so YES you can play online.
Newest release = ESF 1.2.3... download it from a link in the
"Files" section
There are also testing releases of ESF 1.3 called "Open Beta".
The most recent Open Beta is the 18th March 07 release.
Find a link to download it from on
the homepage if you want to help test.
You can have both installed at same time.