garyr_h - 8:49 am on Mar 7, 2013 (gmt 0)
May or may not be. See the Google Updates thread. Many others are also seeing changes right now. IMHO, changing titles DOES affect rank for X amount of days/weeks/months. It's best not to mess with them once they are set.
As for using the SEO plugins to change the titles...I think that's what Google doesn't want. It's obvious SEO and doesn't help visitors. Placing the website name in the title is Google's way of saying, "Hey! If you trust this website name, then click here!"