It depends on who you ask, and what year you're talking about.
Originally(1935ish) it was around 47,000.
It is now officially at 35,000.
If you have a new ultra-scandi-ti lightweight gun, be VERY careful reloading for it. If you have an old manual with the original pressure limit, you could blow up your gun, and maybe hurt yourself very badly.
The original limits can be taken by smith N-frames, most rugers, contenders and similar guns.
Don't ever shoot the hot stuff in an airweight, taurus titanium, or similar gun.