Just to update everyone, Game Maker: Studio's EA version includes the fixes to Spine files and support for mesh deform!!! I have not tested this out to any extent just yet, but when I can move some animations over and add some mesh deforming to start testing I will post here with my results.
Update:
I have yet to really test the mesh deform (working in that direction :S) but anyone who has been trying to use the attachment system might have found it very difficult to set the origin of the image when it's attached and we have seemed or believe to have figured this one out . By default GM does not use the sprites origin or x and y offset defined in the sprite editor to determine it's position. When you place an image on an attachment point it does so in the exact center of the image, to use the sprites origin from the editor you need to take this into account. Here is a quick simple way to translate the origin you denote in the sprite editor into origin coordinates on attachments:
sprite_get_width (ind) / 2 - sprite_get_xoffset (ind);
sprite_get_yoffset (ind) - sprite_get_height (ind) / 2;
It took a lot of messing around with grid based images / trial and error to figure out the weird way it sets the position for images on attachment points and for those wondering attachment points are defined by "slots" within the Spine software and any rotation/translation applied to the bone that slot is attached to does work in GameMaker so it makes a great way to attach weapons/armor onto skeletons outside of Spine.
Update 2:
While this is getting into more GML then Spine I'll add this small footnote regarding attachment points. Rotation through the attachment_create function will always rotate at the center of the image and NOT it's origin that you define. I want to think there is a minor glitch in GameMaker at the moment regarding the origin and rotation of this but for now it's something you will want to keep in mind if you plan on rotating images through the function.