The API's you mention appeared circa ACS 3.4, the current OpenACS is based on 3.2.x (we'll be releasing 3.2.5 "momentarily", as we've been saying for a couple of weeks).
The ad_page_contract and database api's have been backported to OpenACS. I'm not sure what the plan is for making them available in the 3.2.5 release, we've talked about having them available as separate downloads to be patched into the release for those who want them.
I suggest you contact Roberto Mello directly (you can get his e-mail address from https://openacs.org/directory) and ask him about plans to make these backports available. He's organizing the 3.2.5 release while most of the rest of us concentrate on OpenACS 4.x efforts.
