Some years ago, one of my managers used to repeat this "Accenture truism" (or so he designated it): to fix or improve something, first you need the right people, then you need the right processes to help those people work together, then finally you need the right tools to support those processes. People, processes, and tools - in that order.
This is even more true for tech startups than for corporations. As geeks, whenever we face a problem, we often start by looking for a tool to fix it. "Our team isn't communicating properly - let's set up Campfire." "But I don't like Campfire, why don't we use Yammer?" "Yammer and Campfire are so lame, let's just use good old IRC."
This is the wrong approach. Tools by themselves rarely resolve problems in your business. If your team isn't communicating, you need to solve that problem step by step.
First you need to figure out if that's because of a "people" problem. Maybe one member of your team just doesn't want to talk to the others. If that's the case, no tools or processes are going to fix that. For example, many sales organisations try to get their salespeople to communicate everything they know about every client - but salespeople don't want to do that, because it makes them more easily replaceable. Setting up a CRM tool doesn't solve that problem, until you fix the people, by giving them the right incentives to do what you want (or, if that's impossible, either changing what you want or changing the people).
Then, you need to look at the "processes" part of the problem. For example, assuming your team wants to communicate with each other, maybe they can't because they tend to sleep at random schedules in different parts of the world. That's a process problem that can be fixed by, for example, declaring a certain time each day "team time". For example, you can anoint the period between 2pm and 4pm in some timezone as "team time", and require everyone to be available to chat at that time every weekday.
Finally, once you've got the right people and they have the right processes in place to support them, then you can start looking for tools to support those processes. Depending on what you actually want "team time" to look like, you might choose campfire, GTalk, IRC, or any number of other tools. But by now, you can select the tool based on whether or not it supports your processes, rather than whether or not it's the sexy SaaS app of the month.