programming by USB on the CC2511

I would interpret this statement as a "for instance, or it is possible" and not something where software is available to take advantage of this feature.

The CC2510 only boots from its own flash, and not from peripheral devices like the USB interface.
Secondly, "the windows USB driver" is a bit ambiguous, as I'm not aware of an existing USB driver that supports this functionality.  In order to download code updates from the PC to the CC2510 over USB, there needs to be supporting software in the USB driver and application that actually performs the download, as well as the firmware running on the CC2510.  The two things need to agree on which endpoint to use, what the protocol is, etc.

thank you for your help,

I thing, I was not very  clear in my question.

this is the text from the data sheet:

10.2.2.2 CODE Memory Space
On a standard 8051 this memory space would
hold the program memory, where the MCU
reads the program/instructions.
All memory spaces are mapped into the CODE
memory space and the mapping is identical to
the XDATA memory space, hence the
CC2510Fx/CC2511Fx has what can be referred to
as a unified memory space.
Due to this, the CC2510Fx/CC2511Fx allows
execution of a program stored in SRAM. This
allows the program to be easily updated
without writing to flash (which have a limited
erase/write cycles) This is particularly useful
on the CC2511Fx, where parts of the firmware
can be downloaded from the windows USB
driver.
Executing a program from SRAM instead of
flash will also result in a lower power
consumption and may be interesting for battery
powered devices."

If I undestand this text,and other part of the datasheet , we can run a program in SRAM . When the CC2511 is plug to the USB, it dowload the firmware to the flash by using the DMA controller . When it is finished we reset the CPU. 

Do you think we can do this ?

if yes, do you know if some one have down some code and can help us to write it ?

Thank you for your help.

David