As a house churcher since 1996, trying to follow Paul's model more closely, I always supposed Jerusalem was different, or at least different in its beginning. Reading Acts 2, it sure did look to me like hundreds or thousands of new believers were sitting at the apostles' feet each day hearing lectures. But the greek word for "teaching" is a noun. Being devoted to someone's teaching as a system of thought and attitudes is a BIG difference from being devoted to someone's teaching activity on their particular schedule.
This was brought out to me recently during an e-conversation with Alan Knox, who I'm thrilled to say has just posted on the topic with more great greeky insights to suggest Acts 2:42 should make us "picture the early believers attempting to live their lives in accordance with the message that the apostles taught" (Emphasis mine). I recommend Alan's entire post but here's my favorite bit:
By the way, if you haven't heard about Alan Knox yet, he's a student at Southeastern doing his Ph.D on the purpose of the church meeting being for mutual edification. And when I asked Alan about co-existing at SEBTS with such a stance, he said he finds a lot of people saying they agree with him in theory, but not in practice. Well, isn't that special? ;-)
This passage demonstrates how those early believers lived according to the gospel (the apostles’ teaching), and how they shared their lives and their meals with one another. On the day of Pentecost, God did not create individuals who loved to sit and listen to teaching.