If you look on
www.bigbrother.com which is a separate official big brother site owned by endemol, this logo is on there:
, which still uses the "clouds" but is slightly different to the one on the sponsors page look:
the "shine" on the middle of the eye bigbrother.com website is slightly higher than the sponsor one. so maybe the one on the sponsor is NOT the title sequence.
sorry, you cant see the image that well on the official image, try going on the website