I don't think there is any set limit of sites you can have. However, there is a catch. Any site displaying Adsense is now required to conform to the Google Webmaster Quality guidelines. http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=35769#3 If you can create 100 sites with unique content, then you should be fine. If you create 100 sites with copied, scraped or otherwise unoriginal content your Adsense account might be in trouble.
I have hundreds of sites and google do not give a damn how many sites you have as long as you dont go crazy and copy the same content over multiple sites on the same IP block they do not care about dupe content.
Don't think there's any problem with having that many sites as far as Google are concerned, but adding to them and maintaining them with fresh content may cause you a problem.
No problem bro..You can put your adsense code as many sites as you can but don't against Google's TOS
No there isnt a problem. Some bloggers have 1000's of blogs and as long as they arent black hat or spam etc.. they are fine. Why would Google not want lot and lots of advertisers?
But there seems to be a grey area here. We are all aware of Google Adsense TOS but we also know that Google sometimes turns a blind eye to auto generated sites and autoblogs. Google wants as much advertisers as possible so they can't turf out every junk and spam site (imagine how Google would look like if they did?). It seems that it is possible to have too many sites because in all honesty, who can create hundreds of sites filled with rich, original content? It is physically impossible for a lone webmaster and extremely hard for even a team. If you have sites that number in the hundreds then it’s very likely that they have been auto-generated, and in essence you are spamming the search engines. It is a risk if you are using Adsense because you will be in breach of Google's TOS.You might be banned... then again you might not. I think it’s best to cut down on the number of sites and try and have a strategy based on quality not quantity.
They will be more than happy if you have more websites. The most important factor is what you provide to the community: unique and informational.