According to internal Department of Homeland Security documents, it seems that DHS didn't want to monitor Occupy Wall Street and tried to avoid doing so. Apparently, they didn't want to infringe on people's legal and constitutional rights. This surprises me far more than the news that the movement was being monitored.

Via:

The Department of Homeland Security struggled to avoid monitoring or suppressing the Occupy Wall Street movement last year, despite being bombarded with requests from various federal agencies for intelligence on the protests, according to documents released via the Freedom of Information Act.

The documents show that officials in DHS's offices of Intelligence Analysis and Civil Rights and Civil Liberties were keenly aware of the legal and constitutional issues raised by federal agencies monitoring political protesters, and sought to tamp down the appetite for intelligence on the Occupy protesters from their colleagues in DHS and other federal agencies that rely on DHS bulletins and intelligence.

The records also show that the efforts weren't always successful—there are several instances of DHS gathering and distributing intelligence on Occupy protesters without much justification. DHS released 340 redacted pages in response to a Freedom of Information Request we filed for records concerning the Occupy movement; it characterized them as an "interim release," suggesting that more records will be forthcoming.

According to the documents, officials in the Office of Civil Rights and Civil Liberties took a hard line on curbing DHS intel-gathering on Occupy after the Pittsburgh Office of Emergency Management released a bulletin, apparently produced with DHS help, on potential threats the movement posed. "Both myself and [redacted] are somewhat concerned that several items contained in this Intel Bulletin might be advocating surveillance and other countermeasures to be employed against activities protected under the 1st Amendment," wrote one official in an October 7, 2011.