We can not inject JavaScript to Posterous. So looks no way to add AdSence in it.ドロップボックスを使ってポステラスにアドセンス
The main idea is to use an iFrame to render AdSense in posterous page.
1. Get Free Dropbox account.
Here making drpobox account link(It is free.).
2. Get AdSense code.(this ex. used 468x15 banner)
3. Make your-adsense.html in Dropbox/Public/your-adsense.html
--your-adsense.html content(got at 2)--
<script type="text/javascript">
<!--
google_ad_client = "ca-pub-XXXXXXXXXX";
/* XXXXXXXXXX */
google_ad_slot = "XXXXXXXXXX";
google_ad_width = 468;
google_ad_height = 15;
//-->
</script>
<script src="http://pagead2.googlesyndication.com/pagead/show_ads.js" type="text/javascript">
</script>
4. Go to Dropbox site,go to Public folder and Right click your-adsense.html. Select Copy public link. It looks like below.
http://dl.dropbox.com/u/XXXXXX/your-adsense.html
5. Go to Posterous, login > click Spaces > click gear mark(your posterous blog title setting) > select Space Settings > click Cutomize > click Advanced > click Expand.
Edit posterous code.
--I add AdSense before post body.--
</header>
<div class="body">
<iframe src="http://dl.dropbox.com/u/XXXXXX/your-adsense.html" frameborder="0" style="border:none; width:534px; height:38px;" scrolling="no"></iframe>
<div class="inner">
{Body}
then click Save,I'm done!
*Sometime it wont effect to code. edit and need waiting then save it. and also AdSense needs time to show it.
Feel free to ask questions at any time, please.