is there a room for additional enterprise collaboration softwares that compete or co-exist with sharepoint (microsoft), lotus notes (ibm) or other open source offerings?
yes but dont you think all those Small and Medium sized businesses would like to go for a comparable solution with less string attached (something on lines of atlassian or jive)...sharepoint is expensive in long run and in these tough economic conditions with no signs of improving there is still a market for small players
The problem is most SMB want to play it safe (i.e., use Microsoft). There are some that will play with other technologies but then one of the "business types" gets nervous and asks to go with MS.
It is probably easier to get Atlassian and the like into larger organizations. Start with a small group, kick off a pilot, get noticed by other people who want to collaborate/use your information and then grow within the organization. We use Atlassian and that is what we are hoping to do.