Working for me using Firefox under Windows 7 with a 189kb jpeg. Repeated with a 2.6meg jpeg and had a good completion messge but nothing uploaded.
The service is supposed to scale down pictures that are over 1 megabyte in size and it appears to be this function that is failing. If you resize the picture yourself to be under 1 meg then it should be OK.
If you have a Pro account (I don't) you should raise a support ticket otherwise we will have to use the workaround above until somebody at Bravenet gets around to reading this forum.