This one was fairly straightforward.
Started with an almost identical photo. Duplicated the layer.
In the duplicate, set transparency alpha channel, then used the select by color tool with a fairly high threshold to get the branches. Inverted selection, hit delete.
Created new layer, bucket filled with light blue. Rendered fog (a GIMP render that seems to only be available on my ubuntu netbook, but not on my Windows computer. Odd.) White. On the new "cloud" layer, did some lighting effects with a high glow, low shininess, and a light orange light.
Did fog two more times, these times with low opacity (~40%) and a couple shades of orange and pink. Merged the three fog layers and the blue background layer. Put underneath the silhouette layer, but over the layer that contains the original picture.
Duplicated the silhouette layer, selected by contiguous color (fairly high threshold), inverted selection, and deleted. Repeat as necessary until I have layers that contained all of the branches, but little of the lower area. Merge the branches. Select by color so that all of the branches are selected,
select the original silhouette layer, hit delete (this will separate the silhouettes into one layer that contains the branches, and one layer that contains everything else.
In the layer that contains the stuff other than the branches, do GIMPressionist, select the paintbrush04 brush with fairly high numbers for everything. Apply.
Still in the same layer, do a rectangle select, with feathered edges (high number) and rounded edges (high number), select most of the "sky" area, leaving a space around the corners. Hit delete, so that the impressionistic stuff is mostly on the bottom and the sides, and doesn't detract from the branches layer.
Add a border, since if I've learned anything while looking at Flickr, it's that a border makes all the difference. :) Just a regular border, black, X = ~18, Y = ~44. Add another border around that, light blue, X and Y are both 2. Add the text, and save.
Here is the original photo:
