Just to let you know:
There is a free IPSec VPN client for Nokia S60 mobile phones.
http://www.businesssoftware.nokia.com/mobile_vpn_downloads.phpSeries 60 versions 3.1, 3.2 and 5.0 are supported.
I have played around with this and it works with m0n0wall. I have tried both pre-shared key and RSA signatures as authentication. I can access my home network from the mobile phone.
On the download page, you can find a Windows application which helps in creating the necessary policy files. You can also find various documentation.
Topic: Nokia Mobile VPN