nope Patching balance issues and bugs has been a major issue for some console multiplayer games as fixes were held up in certification before finally being released to the public. Uber's John Comes explains the solution to Penny-Arcade thusly:
Microsoft has storage space on the LIVE servers that allow for what they call 'Title Managed Storage', or TMS. TMS is just a place where you can put any file you want up there. So what we did is put a text file with all of our balance numbers up there and when the game starts up it overwrites the balance numbers with any numbers it pulled down off of TMS... which enables us to do things like double earnings nights, extra bacon nights and a few game play balance tweaks...
For example, if I found that Snipers earn juice way to fast, which is actually a concern of mine, I can make the change to the over all speed in which Snipers earn juice, upload it to TMS and the next time everyone boots the game, they'll get the new number. Now granted, if someone never boots the game and is always the host of their online sessions they won't get the change. But, that's going to be few and far between.
While the scope of what can be changed "on the fly" is likely limited, it's a great step for quick balance changes in a multiplayer shooter. It remains to be seen if this solution is viable for other developers for balance changes. Monday Night Combat will be released on Wednesday as part of Microsoft's Summer of Arcade promotion for $15.