Out of the box, Adobe Premiere Elements 7 (PE7) does not support 50p or 60p timelines. The bundled presets are limited to 25i and 30i timelines. This means progressive footage is 'downgraded' to interlaced mode -- PE7 will still edit them and render out your final video, but it's compromised because the editor assumes it's working on interlaced-video.
Anyway, a while back, Adobe posted a CanonHDVpreset for Premiere Pro, which added "Canon HDV progressive modes (1440x1080 30p, 1440x1080 25p)" to PPro's list of presets. The update installs and works in Premiere Elements 7. Then, a user was able to modify Adobe's CanonHDVpreset, and extend it with p24/p50/p60 presets. Basically, it enabled PE7 to create projects with the following timelines:1080p24, 720p50, 720p60, 1080p50, and 1080p60.
Using that patch (elements7_24p_50p_60p.zip), I was able to read the Panasonic 1080p60 test-clips into a 1080p60 timeline, and render them out at 1080p60. I didn't try any real heavy-duty editing (merging clips, fading, splicing, etc.), but I was very surprised it worked at all.
The reason being... PE7 is *known* to have problems reading 720p50/720p60 recordings made by the Panasonic GH1. Opening such a file in PE7 (with or without the preset patch installed) causes the program to hang or slow to a crawl. PE7 seems to have the same trouble with AVCHD-lite (720p30) recordings from the Panasonic FZ35/38, TZ7/ZS3 and other models. It's very puzzling, because the GH1 and AVHCD-lite files max out at 17Mbps, while Canon and Sony's newer AVCHD camcorders produce recordings at the full 24Mbps. And I've never had problems editing Canon AVCHD (24Mbps) files in PE7.
Sadly, the latest version, Premiere Elements 8, removed the ability to add user (hacked) presets. The preset-patch does NOT work in PE8, so while PE8 can at least read the GH1 and AVCHD-lite files without crashing, it can't edit them natively in a proper 50p/60p timeline. (Well, you can do some nice overcranking effects...)
Here's the link to the preset-patch for Premiere Elements 7: http://forums.adobe.com/thread/447974?Start=0