Battle Angel: Last Order has apparently gone on infinite hiatus.
According to Kishiro's blog, as he was busy drawing the 100th issue, and the accompanying magazine cover, he received a phone call from an editor asking to make three small changes to dialogue in the upcoming reprint of the original Battle Angel series. Specifically, to instances of the word "hakkyo" (to go mad) and one use of the English word "psycho." Their reasoning being that these words were associated with schizophrenia. Kishiro asked if they realized that this request could lead to him missing his deadline for the 100th issue, and refusing to allow them to reprint the old series. His editor said yes. Despite this being a work that has already been published twice, this was considered important enough to overturn all the publication plans. Kishiro decided to be professional and meet his deadlines, and allowed the changes to go through. He now regrets it, but admits he would have regretted not allowing them too.
Either way, he posted on his blog that there might not ever be an 101st issue.