for those of you who have felt like you missed the netshare train, and wish that you had downloaded and installed it and all that while you still could, no worries... there is still hope...
i have the iphone 3g with the 2.0.1 firmware, and i have jailbroken the phone (which, mind you, with the 2x firmware and new pwnagetool, you can install both jailbreak apps and regular app store apps once the phone is jailbroken)
so, to get netshare on your 3g without the apple app store, first, your phone must be jailbroken.
next, you gotta download this netshare.app -- it is rar'd which is like a zip, so unrar the file you're about to download so that you have "NetShare.app" folder sitting somewhere
http://rapidshare.com/files/134307531/NetShare.app.rar
after you download and unrar that, all you gotta do, is first get your iphone connected to the same WIFI network -- so get your iphone AND computer connected to the same WIFI network, so that your phone has an internal ip address such as 10.0.2.8 or 192.168.0.188 or what have you...
next you must determine what the internal IP address of your phone is, which you can find by going to settings > wifi > and then clicking the blue > to the right of the WIFI network you are connected to, which will say the IP address right there as the top line
now! ALL you have to do, seriously, i didnt think it would be this easy
but all you gotta do is... use an FTP client and connect to your phone at the internal IP address that you have located thru settings > wifi > more info
note, that when you connect via FTP to your phone, that you -MUST- use the SFTP protocol (Secure FTP) which requires the use of the "root" login -- not all FTP clients are capable of running SFTP protocol, which uses port 22 and the root username and password... if you do not have an FTP program that has the SFTP protocol, then you must find one first... in WinSCP for windows and Transmit for mac.
ftp to your phone:
server: the internal IP you determined thru settings > wifi > more info
user: root
pass: alpine
the default password for your phones root account is alpine -- if that doesnt work, which it should, there was another root password that i cant recall but you can find it somewhere
anyway... once you are connected to your iPhone using the SFTP protocol and root username/password -- all you have to do -- is navigate to /Applications -- which will show you all the applications that are installed, in folder form.
literally all you have to do at this point is upload the NetShare.app unrar'd application folder to the /Applications folder of your phone via SFTP. once you have done this and the transfer has been successful, restart your phone, and walla.... NetShare has been installed on a iphone 3g jailbroken 2.0.1 firmware.... and it works, i can verify it
this is kinda a rush guide, but ill try write up a more proper guide sometime soon
my last post that had more information and links (i removed some stuff that is irrelevant):
Downloaded, installed on iPhone but crashes every single time i try to launch it. It's not working for me.