“I'm sure you are all frustrated, and I'm also sure you will appreciate that we had no idea that Canon were not going to produce the batteries for this unit in a reasonable time frame. There is still no official ETA on them.
We've sold 6,500+ cameras and Canon has sent us only 100 extra batteries. We have back orders of 1,900+ batteries and in common with all other retailers, that list is growing daily. We are very aware that everyone who bought this camera is a professional or semi-pro and needs to have 2 or more batteries, with or without the battery grip.
The bottom line is that we are also at the mercy of Canon. We apologize for the inconvenience. Please do feel free to express your feelings with Canon directly, at 800-828-4040.
Adorama Camera Customer Service Ambassador”
Another tidbit: in this thread on prophotohome, Chuck Westfall says there's good news:
3-17-2009, 09:37 AM
Re: Canon 5D MkII battery
Canon is ramping up the production of LP-E6 battery packs for the EOS 5D Mark II. New inventory is coming into the market slowly at this point, but backorders should begin to ease up over the next 6 to 8 weeks.
Technical Advisor/Professional Products Mktg. Div.
Consumer Imaging Group/Canon U.S.A., Inc.
There's also some good info in this POTN thread about the quality of batteries and details about what/who makes them etc.
Third party batteries?
So, what about 3rd party batteries? Well, as we've discussed before, there are some out there, but are they working and are they worth the risk? Risk? Should you be worried that the battery might be so bad that it would damage your camera? I'm no expert on batteries but I'd hate to have my $ investment damaged by a battery (and yes, there's always a risk that a Canon battery could damage your camera as well).
I have been reading on the forums and there are plenty of comments suggesting that non-canon batteries can work in the 5D mk ii. There are also posts showing that some of the less expensive ones don't quite fit properly and need their own charger. And let's not forget that none of these inexpensive batteries have the ‘smart' features that the Canon batteries have and the camera will not record any info about these knock offs.
DigitalRev.com has recently introduced a ‘smart' battery clone that they say works with the 5D mk ii! I have not ordered one nor do I intend to (well I do have a backup 5D2 battery I got from CameraLensRentals). I've yet to find anyone who's purchased and received one so I can't really tell you anything more about them.