MacBook – share a wifi-connected internet connection over wifi on stock MBP

I don't know if this option was also available in Snow Leopard, but if you are on Lion you could try the following:

1. Set up the native cisco client - if you don't know how, you can use this handy guide I created a few days back
2. Once you have tried and confirmed that everything works, your VPN connection should show up as one of the options in the Internet Sharing part of Preferences Sharing.
3. select the connection, choose on which network connection you'd like to share it and you're done.

This all happens inside the "Sharing" pane of "System Preferences":

1. Select "Internet Sharing" from the list
2. Select "Ethernet" from the popup menu
3. Click the checkbox next to "Wi-Fi"
4. If you wish to secure the wireless network a password, click the "Wi-Fi Options..." button
5. When you've got it all set up how you like, click the checkbox next to "Internet Sharing"
6. There is no step 6