"Telegram ICO: Scam Among Cryptocurrency Scams"
It's so scammy it's spawned baby scams trying to scam off its scamminess.
Got a spam about this today. Not sure if it's the legit scam or one of the baby scams it's spawned. Either way, I reported it for the spam it was and went on with my life.
Oddly, the official Twitter account for Telegram mentions nothing about the ICO, though it's clear that Telegram is really having one. I've deleted Telegram over this crap.