There are now more than 675,000 apps available in Google Play, a noteworthy figure not for the number of apps, but because it means Android is now within striking distance of overtaking iOS as the mobile operating system with the most apps.

For reference, Apple announced there were 700,000 apps in the iTunes App Store during the iPhone 5 launch event just two weeks ago on Sept. 12. The timing of today’s announcement from Google can hardly be a coincidence, and now that the two stores are basically at parity, its worth going back and comparing their growth rates.

Both Apple and Google launched their mobile app stores in 2008 — Apple in July and Google in October, giving iOS a three month lead time on Android. Despite having similar birthdays, the iTunes App Store pulled out to an early lead in terms of app availability. It took the iTunes app store 11 months to cross the 50,000 app threshold, a milestone the Android Market (now Google Play) wouldn’t hit until April 2010, a full year and a half later.

By November 2009, Apple was reporting 100,000 available apps in the iTunes App Store. Google hit that mark in October 2010, 11 months behind Apple. This difference in growth rates between the stores remained fairly steady in 2010 and 2011, with Apple reaching the 250,000 app milestone in April 2010, and Google following 15 months later in July 2011.

However as both app stores have grown larger, Android’s growth rate looks to be catching up to iOS’. Google announced there were 600,000 apps available in Google Play during this year’s I/O keynote in June. Less than a month later Apple reported there were 650,000 iOS apps available during its Q3 earnings call.

While companies like Flurry and Appcelerator have reported developers are losing interest in Android, its clear from today’s numbers and historical data that this doesn’t seem to be the case. With the holidays fast approaching, its likely both app stores will have more than 750,000 apps by the end of the year — it just remains to be seen which app store will reach that point first.