Hipchat is an amazing product which is steadily getting better under the steam of great developers. It is also owned by Atlassian, a company with great execution and a strong track record of successful cross-selling.
So under these circumstances, no, I personally wouldn't enter this space.
Campfire gets a fair bit of attention here, but is unheard of outside the 'startup'/B2B space. The stats they post are laughable - last time I checked it was a few thousand messages a day - which is pretty minuscule.
Hipchat fills a hole as well, but there are literally thousands of different ways to spin 'webchat' and carve a big following out.
That is laughable - as in it can't possibly be right. Can you provide a link to this?
From campfirenow.com: "Over 100,000 people have used Campfire to send more than 60,000,000 chat messages"
60,000,000 messages, over 67 months, works out at 895,000 a month - approx 28,000 messages a day.
Or one message every 3 seconds. Campfire could be run from a single small VPS.
I think it's entirely believable that the usage of campfire is that low. All credit to them, they've managed to get people to pay for something people don't actually use very often.
Let's assume they doubled in size every year - I think that's a good if imperfect approximation. That would mean 30m messages sent this year, 80K sent today. A far cry for "a few thousand".