Alright, because I know no one likes to read an entire transcript, I have done that part for you and all of the most important information from the chat is below. There weren't any ground-breaking revelations, but here are the good bits:

• Headquarters Pro in MW2 has a timer that starts before the HQ is online, so there will be the opportunity to set up a capture strategy.
• Yes, the 25 killstreak rewards the player with a tactical nuke. Once it is used the team with the player or player who uses the nuke wins the match.
• The only classic Call of Duty map in MW2 is 'Wasteland' which is based on the CoD1 map 'Brecourt'.
• Matches are 1v1 - 9v9 depending on playlist type - this carries over across all platforms. 
• There is no character customization.
• Third Person View (TPV) is restricted to MP game types and the view looks similar to the 'Spectator Mode' - some perks will be useless in TPV.
• Lean does not return to the series here...
• Xbox 360 System Link will have Create a Class functionality now.
• There are customizable killstreaks in MW2. Based on the Killstreak List that leaked previously, it looks like you will have a choice on the killstreaks of: 4, 5, 7, 9, and 11.
• Akimbo will allow dual wield for pistols, SMG's and possibly...shotguns.
• There is no record feature/functionality.
• In MP, snipers can be customized to have silencers.
• You can get all 69 stars in SpecOps alone except 2 - one of those 2 will be for the AC130 mission.