"Mark is no longer an employee at Google," a Google representative said in response to an inquiry Tuesday. Efforts to reach Jen for comment were not immediately successful.
Jen's departure comes less than a month after he joined Google as part of a wave of new hires and began recording his impressions of his new employer, including criticisms, in his blog.
Employee blogging is on the rise, sparking increasing clashes between workers and management over the line between appropriate and inappropriate commentary. In one recent dispute, a Delta Air Lines flight attendant lost her job after posting photos of herself in uniform on her blog.
A Microsoft contractor lost his job last year after he took some pictures of Apple G5 computers being unloaded onto the software company's campus and posted them to his blog.
Friendster, known for breaking new ground in online social networking and promoting self-expression among peers, fired one of its employees in August over her Troutgirl blog.
The employee blog issue is doubly sensitive for Google, which became a prominent booster of blogging through its acquisition of Web logging pioneer Pyra Networks in February 2003. The company also has made a point of putting ethics before profits in its business operations, suggesting it holds itself to a higher standard of care than the average for customers and employees.
While details of Jen's departure are unclear, the newbie Googler ran into trouble at the company almost immediately when he decided to record his impressions of Google on a blog called Ninetyninezeros--one zero short of the mathematical term known as a "googol."
Jen began making entries in Ninetyninezeros on January 17, and soon drew the notice of other bloggers. Curiosity spiked when the postings temporarily disappeared about a week later.
On January 26, an edited version of the blog reappeared on the site, with a new entry explaining the on-again, off-again commentary. Gone was the first day's post explaining his reasons for creating the blog, as well as a description of an employee orientation event that vaguely touched on discussions of Google's booming business.
At that time, Jen denied he made the change under duress, insisting that Google "was pretty cool about all this."
News of Jen's job status was posted at Google Blogoscoped. According to an anonymous message in the blog forum, Jen was let go on January 28.