Insider buying
It doesn't make sense to me that Bill would buy shares on the open market when he has many millions of options that are vested and in the money. I think that most of them have a strike price of 10 cents or less. So yes, it's a very good sign if Bill is increasing his holdings in this manner.
Another possibility that I have been thinking about is that Bill did some sort of re-jigging of his holdings, and bought shares in one account or structure and then sold in another. This would explain Friday's dump of shares, since I find it coincidental that the big market sell order that hit the tape was for around the same amount of shares that Bill purchased earlier in the week.
Be on the lookout for more insider reports.