It defaults to 10,000 on 1.2.3; only in 2.0 does it actually vary (conservatively) according to the amount of system memory. You can, of course, change the value.
For example, I have a Conroe-Celeron @ 1.2GHz w/ 1GB of ram and changed the default value to 500,000. Bear in mind that I don't run any packages - just using it as a NAT router with an oversized state table & HFSC (main reason why I didn't go for SoC based stuff like Microtik or running Vyatta for that matter).
Running 3 torrents on one client, I managed a little over 130,000 states but the unit is holding up well:
[image: pfstates2.png]