A beta preview of the TOTP algorithm has been implemented into OTPD, the Open Source OTP daemon I maintain. Aside TOTP, The Feitian c200 hardware token is also supported. Apparently it should be compliant to the TOTP standard, and it is somehow, but the fact that the time seems rounded to the next minute.
The TOTP daemon has been tested also with the OATH Token for iPhone, and it’s fully compliant. You’re more than welcome to report hardware and/or software tokens that works with it.
If you wish, you can check out the sources from Google’s SVN, full instructions are available on the project “source” section.