How many databases can PostgreSQL open at a time?

I want to migrate a lot of single user databases onto a single server
to allow the users to access them remotely, instead of on the
workstations. The databases are quite small and even the most heavily
used ones only have at most a few hundred records added to them
everyday.

The problem is they have a high polling rate, about every 5 secs. If I
migrate them to a central servers how much hardware will be needed for
them to cope?

My initial approach was to create views for each user and use
updateable views and/or triggers so that the applications can work
transparently simply by changing the names of the tables to the names
of the views, but I am wondering whether it will be much simpler to
use individual databases instead.

/voipfc