can you having adsense on your landing pages? I know you can't with adwords, but can you with yahoo/msn?
As far the Google TOS you can. but if this case if you want to be safe send a question to Google AdSense team.
i feel even if it allowed by google,you shouldnt have google ads on it.See landing page is mainly to make your cutomers buy.....and not for them to click on the google ads and leave your page.Dont let 20-30$ go off your hands for a click of 50 cents!!!It really doesnt make any sense.Give your cutomers only one option to click.....to click the BUY button!!!!!!!
I agree with sft_hrt2002. Basically landing pages are to make people buy.Why would you want to drive traffic away from your site for just few cents instead of selling a product?
Landing pages sometimes are just a warm up pages to another page If you the middle man then you landing page will lead to the sales page. If your landing page is you sales page DO NOT put any thing the can destruct you customer from your main target and that is to buy you product. If it's just a warm up page you may consider it depends on the situation.