The FCC has been very clear that it didn't approve of a Marriott International hotel's blocking of convention center attendees' Wi-Fi hotspots: It fined the hospitality company $600,000 last fall and issued a stern warning on Jan. 27 that such wireless network interference by others will not be tolerated either. But what remains murky to IT shops and wireless LAN product vendors is exactly what constitutes illegal "Wi-Fi blocking": *One university WLAN/network architect wrote a blog post earlier this month titled "Are WLAN vendors selling illegal jammers?" and sparked an online discussion among peers, who are trying to figure out if the tools they routinely use to contain rogue devices are prohibited.