InfoPath Dev

In Infopath 2010 I would like to automagically fill in the active user. therefore I need the UserProfileService.asmx located at http://<address of sharepoint site>/_vti_bin/UserProfileService.asmx

We use Foundation 2010. Is it possible that it is not working in Foundation? Or doesn't that matter?

Yeah, WSS 3.0 doesn't have what you need.
You can do the auto-AD magic fill-in with our ADWS Web service which is a cheap add-on (server license) and you can even try it for free for 2-3 months by installing DBXL which has it included for free.

Let us know if you need assistance.