The tokens would work nicely on emails. Standard Marketo Landing Pages would not render those tokens.
The simplest soltuions are:
1. if users are reaching the landing pages from email
Pass tokens such as {{lead.Full Name:default=Not Available}} through URL parameters
e.g. http://my.example.com?full_name={{lead.Full Name:default=Not Available}}&company_name={{company.Company Name:default=Not Available}}
Add a JavaScript to the landing page to read the URL parameters and pre-populate the fields.
http://community.marketo.com/MarketoArticle?id=kA050000000L3ZbCAK2. if users are reaching the landing pages from web navigation
Use SOAP API getLead and use Cookie ID as LeadKey, then pre-populate the field from XML response.
http://developers.marketo.com/documentation/soap/getlead/