I have zero information if these screenshots are legit or just a simple PhotoShop result but according to Swiss Windows Mobile fan-site "Mobile-Devices.ch", bellow you see some screenshots of HTC's upcoming/next TouchFLO GUI which is code-named "Manila".
No further information given so it's not clear if it is real (really from HTC), an HTC development environment or really HTC "TouchFLO 2.0"; also Mobile-Devices.ch hasn't mentioned where they got the information from but from what you can see from the screenshots, it could be real indeed:

Head over to Mobile-Devices.ch for more screenshots.

UPDATE: Original source seems to be "The HTC Insider" Blog. But also no word here if it is legit and where it comes from.
UPDATE 2: Okay, as I've heard from several anonymous sources (thanks for the E-Mails), this is indeed a new user interface, HTC might release later this year - most likely with its upcoming devices (but it might also replace the current TouchFLO as available on the HTC Touch, HTC Touch Dual and HTC Touch Cruise). Nevertheless, it's intend for internal testing and usage only and the files, floating around the Internet aren't intend to be installed on current production devices. If you are not a developer, better don't install anything yet.

Cheers ~ Arne