For Oracle, we essentially make one Oracle connection per Spotlight client. This is not going to change in the foreseeable future.
For UNIX monitoring, both Spotlight on Unix and Spotlight on Oracle make a series of REXEC or SSH connections to the operating system to run UNIX commands and gather its data. While this does mean that there can be multiple Spotlight users connected to the operating system at one time, there is no particular downside to this. Once again, if there are multiple Spotlight clients connected, they will each make their own connections.
Just to clarify the connectivity behavior of the Unix datasources (as used by both Spotlights):
When using the rexec connection type, each refresh of each query makes an rexec connection, executes the command for the query, gets the results, then disconnects the rexec connection. So, on default refresh rates, you can expect a number of rexec connections to be logged for each and every refresh cycle. Since there is no concept of a permanent connection for which to constantly pass data in rexec, we propose no changes to the way this works.
The situation for SSH is somewhat different. Some of the queries have their own dedicated and permanent SSH connection, so such queries only impose one connect per session, not per refresh cycle. Examples of such queries are those which return data constantly, like vmstat.
Users can expect two or three such permanent SSH connections while Spotlight on Unix or Spotlight on Oracle is connected. Other SSH-connected queries behave much like their rexec-connected counterparts, even with SSH. So there will still be a noticeable connection logging overhead; but it should be much lower than when using rexec.