It's probably 256 or something like that. Not anything you have to worry much about. A huge amount of goverments is not always a good thing though, since the ai usually go for the same ones.
Thanks Kulade, yoda. I noticed that in the editor, improvements and wonders under requirements lists;
Advance
Improvement/Wonder
Government
Resources
I think this may be useful. Each gov can require a hidden tech. You can set up regions ie asian, europe, africa, N. and S. America etc. You can pretty much determine exactly what city can build what improvement.
Example
To build Canadian ministry...............India Ministry
Advance = N. America........................Asia
Improvement = Harbor........................Harbor
Gov = British.....................................British
Resource = Iron.................................Iron
Resource = Copper.............................Copper
You have two buildings - one civilopedia entry - and both can auto produce the same unit say colonial infantry or different units.
If you make the improvement a sm wonder or a wonder, it opens up even more possibilities.