Finally? Yes, that’s what the users of the Toronto-based photography community 500px will be saying today, as the service publicly launches its long-awaited Lightroom publisher plugin. Although often pitched as a Flickr alternative (ahem), 500px is actually targeted more towards professional photographers and those who make a living off selling their photos, than is towards the mainstream consumer user base who needs a place to archive hundreds of baby photos and vacation pics.

And that’s why the Lightroom plugin is such a big deal.

The 500px user community has been clamoring for this plugin for some time now, since it’s been a bit of a hassle for users of Adobe Photoshop Lightroom to get their photos from Lightroom into 500px. But with the new release, which was tested by over 500 photographers during its beta period, it’s about to be much easier.

The plugin now allows photographers to:

• Publish photos to a public profile or a personal portfolio
• Create and manage portfolio collections
• Edit titles, descriptions, and other metadata and sync it with a 500px profile or portfolio
• Read and write comments for your photos from Lightroom
• See your individual photo statistics, such as views, favorites, votes and rating

The new plugin supports Lightroom 2 (in export mode only) and Lightroom 3 (publishing and export modes) and is now available as a free download here.

Last month, the startup released its iPad application, which saw over 100,000 downloads in the first week alone. But 500px’s Creative Director, Evgeny Tchebotarev, is being a bit cagey when it comes to revealing the actual size of the 500px user community. He says that they’re waiting to hit a “big milestone” before the reveal, which should come soon. He will say, however, that the startup increased its user base 15 times since January, and expects to see a 20-fold increase by year-end. In June, the company reported going from 1,000 users in 2009 to over 85,000, with around 45,000 having joined in the previous three months. And in October, the company said it was seeing 6.6 million visits to its site per month, so you can extrapolate from there.

500px raised $525,000 in Series A this summer, with investment from High Line Venture Capital, Deep Creek Capital and ff Venture Capital. Now that the Lightroom plugin has launched, 500px says it’s working on a big update to the iPad app, which will also be out soon.