For some reason I actually liked the plot and it made sense when you tied all the dialog pieces together.

SPOILERS GALORE (in a thread filled with them anyways)

Shepard blames the Ultra-nationalists for the nuke going off in MW1 and since they've taken over Russia he directs that blame towards Russia.

Shepard recruits your first character for a CIA deep op and pairs him up with Makarov then leaks that information to him.

Makarov uses this information to stage the "No Russian" attack and then plants you at the scene.

You're identified as having been recruited by the CIA and a US Ranger so Russia plays the 'victim' and gets revenge by attacking the US.
^- Think 9/11 where Al queda is the CIA. Since you were attacked by an agency sponsored by a country, you attack the country in response.

During the attack several key VIPs are assassinated and the US leadership is pretty much defaulting to Shepard.

Price is rescued and has a bone to pick with the Russians for his 'rescue' in MW1 and since the Russians are attacking the US he launches the nuke from a Russian sub to EMP the invaders and cool things down on that front.

Shepard capitalizes on the nuclear launch and gains full authority to do whatever it takes to 'stabilize the situation'.

141 is sent to two of Makarov's strong points to try to catch him and wipe him out. Detailed documentation of the attack in No Russian is found and a plot shift occurs.

At this point 141 is expendable and Shepard tries to wipe them and Makarov out at the same time. If you think of an all out invasion/war with Russia as Shepard's ultimate objective then the reason why it all plays out this way is because of a change in conditions. Shepard worked with 141 before this point to try and catch and silence Makarov so the true nature of the attack isn't released to the Russians and the US invasion is stopped. After this point he has documentation of the attack which he can doctor and release as he sees fit and full military authority without limits so the Russian invasion is no longer needed for martial law and both Makarov and 141 are liabilities because they know and have witnessed the truth. Price strikes a deal with Makarov and the end phase plays out.

Either MW2 is going to be 'episodic' in nature with additional campaigns released to continue to story line (it ended on a much BIGGER cliffhanger in MW2 than MW1) or MW3 is going to be used to continue the story. Either way, I want to see how the plot ends because there are a lot of unanswered questions left over. Personally I'm betting on episodic since they even went to the trouble of naming the campaign "For the Record".