Well, to be succinct, yes and no. The 2 minute best man speech is out there, but to call it a speech might be pushing the boundaries of reality a little. In the UK lot of best men don't relish the thought of speaking, and more accurately the pressure of making people laugh. To that end they think that the best policy is to be up there as briefly as possible; in America wedding speeches tend to be a lot shorter and more efficient, but even 2 minutes is maybe a little too efficient - and don't get me wrong: nothing is worse than talking for too long.
All best men really need to shrug off the idea that this is something they need to get over and done with. Yes, you may not relish the idea of speaking in front of people, but nothing is going to look more peculiar than standing up, blurting out several hundred words, and sitting down 90 seconds later. Yes, people always speak more quickly when they're nervous and if you're planning on 2 minute speech, then it'a almost certainly going to be a lot more brief than that. Speaking for 2 minutes as a best man is really little more than a toast - if you try to cram too much in there, it's going to look like some weird word forfeit and you're going to be spitting out text like a Gatling machine gun.
Yes, the idea of a super short speech is appealing for the best man, but in reality it doesn't really work well for anyone else; the chances of saying something genuinely funny are remote because you've got to have enough time to say what this guy really means to you as well. Nearly every single person who came to me for a 2 minute best man speech, always ended up with a 5 minute speech, and in some cases much longer. If you get your head around the fact that the best man speech can be something you really enjoy and dine out on for years to come, the temptation to make it a 2 minute blitz will soon dissipate.