Thematic Consistency is the principle that a web link should serve essentially the same information to all browsers. Adapting content to better fit the target platform is good but redirecting requests for a specific image or news item to your site's homepage spoils the user's experience and discourages them from using or linking to your site or web service.
Sites that break thematic consistency get a place of honor in the WapReview Thematic (In)consistency Hall of Shame. The latest honoree is Google Plus! That surprised me as Google is one of the few big companies that seems to understand the web on mobile devices. It's all the more surprising that the problem occurs with Plus, a product that Google is lavishing a lot of effort on currently. I'm sure this is a bug rather than intentional and I hope that Google fixes promptly.
Google+'s thematic inconsistency problem occurs when someone shares a link to an individual Google+ item on Twitter or in a blog post. For example, here's the permalink to a Google+ post by MobileBurn's Michael Oryl https://plus.google.com/113528147156289620389/posts/3e13HVX1kLB
If you follow that link in a desktop browser or the Android or iOS browser everything will work as it should and you will end up on a page showing Michael's post (first image, above).
But with most other mobile browsers including Opera Mobile, Opera Mini, UC Browser or the
bada, WebOS or Symbian Belle or Nokia S40 Proxy browsers, Google will redirect your request for Michael's post to your Google+ home page showing your own Google+ stream (second image, above) rather than the linked post!. That means the permalink is broken!
Update 1-Aug-2012: Google+ post links now work in the bada and Nokia S40 proxy browsers, still broken in Opera Mobile, Opera Mini, UC Browser and the WebOS and Symbian Belle browsers.
Until Google fixes this bug, do your friends a favor and don't share links to Google+ posts by email or on Facebook or Twitter.
This bug only occurs if you are signed into your Google account. Sign out of Google and Google+ permalinks open the correct page. They do go to the desktop version of the page rather than the mobile formatted one which is probably another bug, but not a serious one as most modern mobile browsers handle Google+ single item pages well.