Is it copyright infringement to maintain a blog in which I am 'curating' the content by selecting what I think is the best content 'out there' based on certain criteria?

If you are only posting links to the other articles, the area is not very gray - you will not be considered to be infringing. If you copy the articles to your own blog, you will clearly be infringing. There are very few circumstances under which you can take content from another site and post it on your own without violating copyright law. Claiming fair use is risky, and for most purposes is only going to allow short excerpts.

As others have stated, it is copyright infringement to republish another's content without permission. But no one has mentioned that there are ways to republish articles legally, by licensing them for reuse, directly from their blog or publication to yours.  If the blog or original creator has a republishing toolbar ( a free plugin for authors/publishers/bloggers), the process is automated and instant. The author grants a license, and you get to republish their content with permission. This toolbar can be found here:  http://iCopyright.com (disclosure: I work with iCopyright).  iCopyright  has created a content network for finding and republishing  rights cleared, content from various sources, as full articles ... and a syndication feature for those who want to add their content feed to the network.  http://offers.icopyright.com/repubhubabout-0 Or ... if the original content creator does not have an interface that enables you to curate and reuse their content easily, you can still contact the author, and ask permission --and then add the appropriate code that tells Google that your article is not the original source.

Regardless of how much work you are "curating," if the work is not your own, you need to give credit to the author or you are guilty of plagarism.  In some countries this is considered honorable.  In the US, it is not.