That recently?

The Stiletto, writing at Blogger News Network quotes Bob Burney as referring to the "notable change in how the Mormons present themselves, beginning about sometime around 2002, around the time of the Winter Olympics. Burney claims that prior to that, for instance in the there was "not a readily apparent note for Mormons to identify themselves as form of Christianity" and "that suddenly, around 2002, they wanted to be accepted as a form of mainstream Christianity....even a peripheral study of Mormonism will reveal that the Jesus of Mormonism isn't the same as the Jesus of orthodox Christianity".

After further discussion of ways in which the LDS church seems to want to hide its distinctive doctrines, he asks the Mormons to "Be candid"

That's fair enough. But the story goes back further than that.

First of all, the Church of Jesus Christ of Latter-day Saints adopted that name in 1838, although even this was not a new claim: It was initially organized in 1830 as the "Church of Christ". Although those who did not believe its teachings denounced them as blasphemous liars, few doubted that they at least claimed to be Christian.
Fast forward past the official and unofficial persecution conducted up to 1890 over polygamy. Starting in about the 1900s, Mormonism began to be tolerated and accepted in the United States. Though still marginalized and considered unworthy of serious attention, they were often confused with other Protestant denominations.

It has been noted that as the Mormons began to gain more nationwide attention, for instance with the 1960s run of George Romney for the Presidency, they began to appear to move a little more toward the Christian mainstream. But there is another factor involved. Also about that time, a number of disaffected and former Mormons began work at "digging up dirt" on the Mormons, attempting to disprove and discredit their beliefs. Fawn Brodie, Walter Martin, Dee Jay Nelson, Jerald and Sandra Tanner, and Ed Decker were some of the most prominent names. These were eagerly swept up and their findings swallowed wholesale by the Christian countercult movement, and endorsed by mainstream evangelical ministers. But, while there is some solid historical truth to their claims, there is also a great deal of half-truth, innuendo, distortion, spin, and outright falsehoods in their writings. They demand Mormons meet a high standard of strict integrity which they themselves cannot. For the problems caused by relying too heavily on the testimony of enemies and defectors, one only need point to the war in Iraq.

This is approximately when the "Mormons are not Christians" idea began to gain momentum and publicity. It has since become standard evangelical doctrine. In response, Mormons fiercely resist the charge that they are counterfeit Christians or not Christian at all, but will readily admit and even embrace a claim of not being Catholic, Orthodox, or Protestant. If Christian orthodoxy is characterized by a Bible plus post-Apostolic creeds, Mormons proclaim themselves to be Bible plus Book of Mormon plus additional revelation: Different, to be sure, but their acceptance of that common core distinguishes them from Jews, Muslims, Hindus, and any other recognizably non-Christian beliefs.

It may indeed be the case that in recent decades, Mormons have shifted noticeably toward an emphasis on the common beliefs that they share with evangelical Christians, It may well be that they took advantage of the increased publicity that the 2002 Winter Olympics brought. They are also taking advantage of the similar increase in publicity that Mitt Romney's candidacy is bringing. But these changes are in the peripherals, not at the core.