This discussion came up on Brighthand and it seems that the replacement battery shown on HighTech.com is similar (in size) as the EXTENDED HP Battery.
If you check on HP for the part Part Number: FA192A#AC3, you end up there:
http://www.shopping.hp.com/cgi-bin/h...me=product.cgi.
Another thing; the battery shown is 1800mAh vs. 2000mAh (description) !?!