Well, probably not, but you should always be on the lookout anyway. Read this delightful blog entry about Mozilla and data collection.
A few things. People generally don't want personally identifiable information about them on the Internet. Even if Mozilla Foundation does a better job at anonymizing the data than, say, AOL did (long story short: AOL released what users were searching for and assigned each user a unique ID; many users had searched for their own names or other personally-identifiable data, and so the IDs could be traced to specific people), there's always a chance that collected data could be stolen by hackers before it's anonymized, by compromising browser security (every major browser has security vulnerabilities discovered all the time... sometimes they even get fixed) or the server that collects the data (servers get 0wned all the time, though not so often when administered competently, as MoFo is likely to do).
Fortunately it is open-source. If Mozilla Foundation decides to collect web usage data on users a fork will actually get some attention (unlike the current forks, which have occurred because of the clash of Mozilla Foundation's rather corporate take on branding and the four or so freedoms of Free Software, which only dorks like me care about). Firefox has long had features representing interests other than its users', and the geek community has stood by because they've lined up closely enough. But I think even a pretty benign-seeming (to the bureaucrats, marketers, and web designers that love this proposal) data-collection feature could send important parts of the geek community to forks, or even to other browsers like Konqueror, Opera, or even IE.
EDIT: the link to the Mozilla branding thing up there is old, and doesn't refer to any of the specific issues relating to branding trademarks and software modification that caused the forks, but it's a decent example of Mozilla corporate speak, of yet another Mozilla guy that is standing above his community rather than within it. "If we want to have an impact we have to trick people into it with clever branding and marketing." As a side note, Firefox "evangelism" has always creeped me the fuck out.