Haze - yes NSM will gather and report all log data from an SRX box. A couple of things worth noting:
1- As Dominick said you will need to configure a specific log file for the NSM server to read. This log file (default-log-messages) is what the NSM server reads. The choice of facility and log level will determine what gets pushed into NSM. For troubleshooting I would start with "any any" - you also have to have the second line (structured-data) so that the messages are formatted so that the NSM server can read them.
2- Then apply the standard term "set then log session-init (close) for the policy you want to have traffic logged for.
This works just fine - I do it on my boxes.
I will also say that I am running 2010.2 with various flavors of 10.0, 10.1 on the SRX/EX/J-Series boxes. Can't say how well it all works on prior releases.
Let me know if you have any other questions.