I was employed at Mitel back in 2006 when the company filed for an IPO the first time. As the only "blogger" at Mitel at the time (writing here on this site), we had a number of internal conversations with the communications team about what I could and couldn't say. The rules for the "quiet period" of an IPO are very strong and at the time it was unclear (to me, anyway) about what could be said in social media. The result, as I recall, was that I didn't write about Mitel much at all during that time.
That IPO attempt ended with the Inter-Tel acquisition in 2007 (which also ended my employment at Mitel) and the company has been working away privately since that time.
I wish them all the best with this second attempt. There are some great people there and they have some great products and technology. Congrats to Sir Terry Matthews and all the rest there!