Just because you're using scraped content from other sites doesn't mean you have to spin them to appear unique for your own site. When you set up an autoblog, typically you're making a new website targeted for a particular niche. In doing so you choose a decent theme you like and selecting several different rss feeds from other blogs to provide specific type articles. The very process of collecting articles from the various sources and repackaging them into your own blog has created a unique website. Even though the content maybe duplicates of posts on other blogs, the way you've chosen to use it on your website is enough for it to be considered unique content. Google really doesn't care how many websites have pages with the same content. What it does is makes a choice on which one it thinks is the best choice and that one gets shown in the serp. The other pages are still in the index though and if one of them starts getting promoted alot and moves up in the index then that's the one that'll start getting shown in the serp when someone searches for the right keywords.
Technically the scraped content used on autoblogs isn't considered duplicate content anyway. An autoblog is just an aggregator website, and all the content you collect from rss feeds from other websites is considered syndicated content. You're riding the grey line a little more when you use other methods to scrape the content but it's still basically the same thing. Scraped content just stands a slighty better (although still mostly unlikely) chance of getting a dmca complaint than content collected from feeds.
If you're planning to submit content to article directories, or you're scraping content that's very likely to receive a DMCA complaint then you need to consider using article spinners and making sure the articles can pass copyscape. If that's the type of content you're scraping then you might want to use one of the suggested wp plugins, but otherwise you shouldn't need to worry about it.
If you're just using the articles on blogs and your own sites then it really doesn't matter. The fact that you get A LOT of content from other sites shouldn't be a big issue, unless the other sites have a really strong position in the SERP for those pages. It isn't a matter of receiving a penalty for having the EXACT content as a page on another site, but simply a matter of whether you can outrank that other site with your page. In most cases, if you want to outrank them with their content on your own pages you probably can.
If the combination of those pages on your site creates a better overall website, and provides better targeting of keywords for your niche then you're website can potentially do better overall in the SERPs than any of the sites you took the content from.
Here's a video from GoogleWebmasterHelp that's worth watching. Part of it discusses some of the myths regarding duplicate content.
http://www.youtube.com/watch?v=6hSoXutuj0g&feature=channel
Here's some other recent bhw threads discussing the topic of duplicate content in more detail:
How unique does content need to be for google?
How Does Big G treat spun articles?
What are the risks of 'spinning' content?
How does google determines duplicate content
Guide - Duplicate Content - Myths & Facts
SEO myths and reality
do any of you guys just not give a shit and blatanty copy content from wherever you want
Posting the same article to 1000's directories - good for backlinks or not?
No Such thing as duplicate content - Revealed
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