If you've ever dissected port scans, the *vast* majority of them scan known ports.
Still security by obscurity is still not a concept worth promoting though. Just setup the services properly on the standard ports.
For example, I run a number of SSH services set up on the standard port 22.
But they are correctly setup with public key authentication, so I don't care about port scans because I know they'll be dropped by SSH if they try to connect. The logs are also easily filtered out.
The other problem with non-standard ports is you can easily run into filtering issues... WiFi hotspots for example might only allow a subset of common ports.
But then you knew all that already.....
