TripAdvisor is far from the community comment tool that Yelp.com and 43Places.com are, but I would guess that they are looking at those sites for future development of their own.
From their website:
The largest site for unbiased travel reviews gives you the real story about hotels, attractions and restaurants around the world. Stories, secrets and special places from people just like you. Search, travel, then share your own experiences.
- 3,000,000+ unbiased reviews and opinions you can trust
- Updated every minute, every day by real travelers
- "Been there, done that" inside information
- The best deals for your travel dates