I decided with some of the confusion going on about what happened to the Malaysian flight yesterday over Ukraine to try to settle some questions about the system that was most likely used to bring down the plane. I'm no weapons expert, but a little bit of online research gave me enough to at least give a general idea. More below the fold.
An example of Buk(SA-11) missile system
As you can see from the photo above, the "Buk" missile system, as the SA-11 is called by the Russians, is no shoulder-fired or man-portable system. This is a fairly large vehicle, sporting missiles that are approximately 18 feet long and weigh on the order of 3/4-ton apiece, requiring a specialized loading vehicle to lift and load the rockets. The vehicle these missiles are carried on is a lightly armored tracked vehicle capable of speeds of up to 40 mph on-road. The vehicle typically has a three-man crew and is usually operated in conjunction with a separate command and control and radar control vehicle and , but it also has the capacity to track and select it's own targets.
The missiles themselves include a 70 kg high-explosive fragmentation warhead and semi-active radar for homing in on targets. The fuze is a radar-proximity device, so the missile does not need to directly impact the target to detonate. The SA-11 can be brought into firing preparation in about 5 minutes, and can begin tracking a target at a range of about 20 miles lock in on a target and fire within 22 seconds. It can be returned to road-ready to move it's position within another 5 minutes after firing. So with a highly-trained crew, an SA-11 could drive into position, prep for firing, acquire a target and fire, and be back on the road moving to a new location in under 11 minutes.
Another example of the SA-11
I guess the take away from this is that as I said in the beginning, this is no random piece of equipment that some terrorist is going to pick up off the ground and use. It's not portable in the sense of a shoulder-fired rocket, and the technical equipment is going to require some knowledge and training in order to use it with any effectiveness.
If I've missed anything of significance, or am in error on any specifics, please make note in the comments. As I said, I am not a military arms expert, what I've posted here is a result of internet sleuthing on a few sites dedicated to military hardware.