"Random" bag searches don’t appear to be happening. There are heavily armed T Police (and the occasional National Guard MP) at key points on the Red Line, but they seem to be largely content with standing around gabbing. True to expectations, their distribution is not terribly consistent. While there are guards stationed on each level at Park Street, there’s no one at Boylston, all of 1/4 mile away. Basically, if you did get turned away at Park, you could walk a block and then wave at the guards from your seat on the train.
This is not to say that bag searches aren't happening, though. Orange Line trains are being stopped and everyone’s bag is being searched. The Orange Line is the "ghetto" train, so I guess it's not that surprising that they’d be looking for malcontents there. The key thing here is that they’re not being searched as they board, so again, while the Convention itself is being protected, there's nothing preventing determined individuals from blowing up trains full of commuters. The only bag searches on the Red Line that I've heard about have involved sketchy hippie-looking types with duffles, a practice which really looks more like harassment than the random searches promised.
For the record, I'm really not liking the overwhelming presence of various flavors of security. It's actively creeped me out at a couple of points, most notably on Monday when I was passed on the Commons by a fleet of slow moving motorcycle cops, and yesterday when cadre of identical black SUVs with Maryland plates drove quickly down Washington Street. I've learned that while mounted police from Providence appear to have no problem whatsoever with having their pictures taken, the T Police and the National Guard MPs are significantly less amenable. Yesterday, both groups used passive intimidation tactics (such as having one of their number walking purposefully in your direction, or shifting positions so the back of a head always seemed to be filling your frame) to get photographers to move on. Nothing explicit was said, but it was clear we were not welcome.
Final words for today? I didn’t score a pass into the DNC, so Jesse Jackson didn’t step on my foot. The MBTA still hasn’t gotten back to me about my photo permit, and at some point yesterday, I lost my NLG "No Search" button.