Please read all of the information provided and note that this issue has been resolved. Adsense Update
There is nothing more to be said. The wordpress.com software will continue to strip out any adsense code you place in your blog. Any other advertising you place on your blog will make it subject to deletion.
If you do not wish to wait then wordpress has an alternative. You can hire a webhost and download the free software from http://wordpress.org and run adsense ads on that blog immediately.