Did you know that both Kanye West and Jay-Z are on Google Plus? Each has less than 1,000 followers at time of writing, so chances are you didn't. Now that Google Plus is going mainstream, or at least experiencing rapid growth in user numbers, you'd think that entertainers of Kanye and Jay-Z's popularity would be using it.

As we discovered earlier this year, Kanye West has huge followings on both Twitter and Facebook. He was a regular Twitter user at that point, although he's only tweeted 4 times since the beginning of July (the last time on 21 July). Google Plus emerged onto the scene at the end of June, and Kanye posted his first message there on 27 July.

According to analytics firm comScore, Google Plus had 25 million unique visitors as of July 24 and is growing at a rate of roughly 1 million visitors a day. That's rapid growth, and it translates into a massive marketing opportunity for musicians, artists and others in the entertainment industry.

One of the most popular music entertainers around is Kanye West. The rapper (or probably more likely his PR team) has begun to use Google Plus to promote his new album, a collaboration with Jay-Z called Watch the Throne. Kanye has 885 followers on Google Plus at the time of writing, but is following none.

It's a mere dip of a toe in the waters for Kanye, when you consider the popularity of his Twitter account (3,973,470 followers) and Facebook Page (7,999,755 likes).

Meanwhile, Kanye's rapping partner Jay-Z has just 416 Google Plus followers. His first message on the service was 30 July. Jay-Z has 418,168 Twitter followers and a massive 9,781,922 Facebook Page likes.

Clearly, Jay-Z has bragging rights over Kanye West in terms of Facebook followers!

However, it's good to see that record labels have begun to experiment with Google Plus for their clients. One of the more interesting profiles is that of Lady Gaga. She has 5,289 followers at time of writing. The account is updated regularly, including by the lady herself.

Perennial social media early adopter, Trent Reznor of the band Nine Inch Nails, isn't using Google Plus much at this point. Reznor has 21,317 followers, but has posted only 4 times since joining on 6 July.

Google Plus may be going mainstream in terms of overall user numbers, but big name entertainers are still in the experimental stage. It'll be interesting to track whether this changes over time and if Google Plus will ever challenge Facebook and Twitter as a mainstream promotional tool for entertainers.