First of all: We got a new patch a few hours ago that unlocked Jakiro,Huskar and Batrider (fire-themed). Aside from that, there are many Bot-improvements. Bots are pretty strong and smart right now. At this rate, we won't even need human opponents.
You might have heard rumors about the "confirmed" release date of Dota 2.
E.g. DotaCinama (featured by dota2.com lately) posted:
"The game was "confirmed" recently to be launched in February."
The idea is this:
56 heroes are now in Dota2. 104 -56 = 48 heroes remaining then => 48/3 = 16.
If they continue releasing 3 heroes every week the Hero Pool will be completed in 16 weeks (which is February 2012).
But that's not entirely true. You can't rely on smooth 3 heroes/week. There are also several other aspects like:
VAC protection, servers, optimizing the engine (right now it's RAW data, you'll need a powerful PC to play the beta) and much more.
My advice: Don't listen to those rumors. Aside from spreading false informations, DotaCinema happen to be scammers which was revealed a week ago ["selling" Dota 2 betakeys]. The only source is the official www.dota2.com
Everything else is just a rumor or marketing attempt to get visitors to their page.
Besides: The plan to release every hero and ship Dota 2 was abandoned. Instead, IceFrog said:
"Welcome to the new plan: We're going to take the current version of Dota 2, which has The International set of heroes, and get it out there as fast as we can."
That means that Dota 2 will be out BEFORE all heroes are ported.
I'm pretty sure that by the end of this year, Dota 2 beta will be either in an open beta or something very similar to it.
Patience is a virtue...