I still don't get why they apologised... There was nothing wrong with the tweet.
People need to chill out.
It gave the perception that if it didn't recieve 100,000 retweets the full amount wouldn't be donated.
More than that, I think the perception was that Microsoft was turning this into a marketing opportunity rather than being charitable. They may have a point, $100k is chump change to them.
But isn't re-tweeting a good way of raising awareness of the cause as well?
Sure if it was along the lines of "tweet 'Microsoft is awesome' now to make us donate...." but the only thing linking it to them was the twitter name, and a link to a website helping people effected by the tragedy .