This morning we were greeted with the surprising news that four year old blogging site Posterous has been acquired by Twitter.  My first reaction was “holy shit!” It was difficult to even digest that news as there are several factors that made no sense in this acquisition and only one does.

Twitter is a short post service that serves as an information network and to many people, a messaging platform. It doesn’t go beyond 140 characters. Posterous on the other hand, is a lot like Tumblr. It’s a full form blogging network that also lets you share various forms of media including images, audio, video, pdf, and other documents.

So what’s gonna happen to Posterous?

Many saw Posterous as a direct competitor to Tumblr but it never caught on to the same scale and popularity as David Karp’s company but it did have innovative features and apps, notably the super simple direct email post for any content to Posterous.

Instead of having unique email addresses for people to send to, you only have to send an email to post@posterous.com and it will handle it accordingly based on your email address. It then evolved its platform from individual blogs to Spaces which is directed more towards photo and video sharing for families and organizations.

Apparently Twitter seems to be more interested in the team rather than the product, especially given what it says on the company’s blog post regarding the acquisition. What this likely means is that Posterous Spaces may face an uncertain future.

The blog post by Posterous founder Sachin Agarwal said that the company will make ample announcement should there be any changes to the service. The post on Twitter’s blog also said the same thing and even added that it “will remain up and running without disruption.”

So what’s next? First of all, the company’s entire team will be at Twitter, working on projects to improve and enhance Twitter. This means that down the line, once the acquisition is completed, Posterous won’t have any engineers to work on it and it will have to shut down the service, unless for some reason Twitter sees a reason to keep Posterous alive and make it a product of its own rather than shutting it down, which is unlikely given that both Twitter and Posterous have said that they will make content exporting and backup available soon.

The most telling part of the acquisition FAQ is this: “We’ll give you ample notice before any changes to the service and we’ll share clear instructions about how to move your content to other services. In the meantime, your Spaces will remain up and running without disruption.”

“In the meantime,” so yeah, looks like Posterous will be shut down later this year after four years.