thank azkay.
it worked well on the N900 and Skype after installing all of followings debs:
libglib2.0-cil_2.10.4-1_armel.deb
libgtk2.0-cil_2.10.4-1_armel.deb
libmono2.0-cil_2.4.3-1_all.deb infi-bit:
libmono-corlib2.0-cil_2.4.3-1_all.deb
libmono-posix2.0-cil_2.4.3-1_all.deb
libmono-system2.0-cil_2.4.3-1_all.deb
mono-runtime_2.4.3-1_arvmel.deb

user#: sudo gainroot
user#: apt-get install gstreamer-tools

and than from the N900 internet browser installed Smartcam.

used it with skype, it works well, streaming live, no delay.
but didn't work with the Google Talk Plugin Video and Google Hangout video chat.
the plugin version I am using is the "Google Talk plugin v2.2.2.0" and Smartcam 1.4 on pc.
I can see the smartcam option is available and selectable on googletalk's chat settings; but when i select smartcam as preferred device and start a video conversation, it only shows black-screen.

is there a way to get the Smartcam working with the Google Talk Plugin Video? if I change the versions if G plugin or smartcam will it work?