Hi, i need to control almost 10 7-segments time displays, 10 clocks. It's possible do that whith only 1 arduino? What's the best option? I have see https://www.sparkfun.com/tutorials/407 , it's say that I can connect 3 of then to one arduino, but i need more.
You could do it with shift registers, one per digit.
Adafruit have i2c 7 segment
and how many of them may i control with a single arduino?
I imagine the I2C device is a single address, so realistically, only one, unless you're into bit-banging it.
I don't know the maximum number of shift registers you could connect - probably limited by the size of your wallet / power-supply.
Are they displaying the same time or different times?
diferent times
8 on i2c
I stand corrected - four or eight addresses selectable by jumpers.
However, eight is only very approximately equal to ten.
8 is > 3
So 8 on the hardware i2c bus, you could implement a 2nd i2c bus using;
http://code.google.com/p/rtoslibs/downloads/list
DigitalIO20130221.zip
Is that better ?
I seem to remember that Crossroads had an Arduino clone that included a bunch of shift registers and so on which made it ideal for this type of project.
Yes, the board can control up to 12 common anode digits. More if you daisy chain boards.
http://www.crossroadsfencing.com/BobuinoRev17/
A variation of the board controls these swimming pace clocks, with 12V powered segments.
http://www.kiefer.com/kiefer-15--digital-pace-clock---rechargeable-products-1776.php?page_id=160
http://www.kiefer.com/kiefer-31--digital-pace-clock---rechargeable-products-1775.php?page_id=160
Apparently they are flying out the door as fast as they can assemble them.
Or, you can daisy chain MAX7219s if using regular 5V common cathode 7-segment displays, each MAX7219 can control 8 digits.
A single MAX7219 can control 8x 7 segments and you can daisy chain several (up to eight I think) together.
Its like there's an echo in here 
I don't think there's a limit on how many can be daisychained.
2 would be plenty as the OP is only controlling 10 digits.
CrossRoads:
Its like there's an echo in here
Oops, did not see the comment at the end of your post, I got as far as the pictures and skipped.