Have you thought about looking for a different preschool? Did the comments at the conference just come from out of the blue? Our kids all went to Montessori preschools but we were never taken to task for having kids that were ahead developmentally - each child was celebrated for what they accomplished at the preschool, and the skills they focused on their were not traditionally academic for the most part - they were activities that built a great foundation, and a fundamental part of the curriculum was allowing the children to choose their own work and work at their own pace.
OTOH, if the comments came up because you asked about what your child was being given to learn (this is just my guessing one reason they might have happened...?)... then maybe consider a different philosophy preschool than Montessori.
In either case, it sounds like maybe the preschool isn't the best fit.
Re blogs and talking to others... I have always found that it's much more pleasant and easier to ask questions of other people about how their children are doing and listen to their stories first - and then when they ask about my kids, answer specific questions. Sometimes it seems like the world thinks we are bragging but honestly, I have listened to other parents talk about their kids (without me asking first) about *whatever* (doesn't have to be gifted kiddos) and it can be boring! I am very proud of my kids, but I don't feel like I have to share a lot of it with other parents.
One thing I found when my kids were young though is that when I took them to things like summer science camps, art workshops, etc, there was a higher percentage of kids who were more likely to be gifted in the mix and parents who weren't going to faint from shock if your two year old was reading or painting like Michelangelo

Hang in there - remember that what's really important is your kids and your family life, not what the rest of the world thinks of your parenting. Also sending you a big hug!
polarbear