Sales numbers are probably in the range of 5000-10000 units per month. The author of "How to Use the Amazon Kindle for Email & Other Cool Tricks" says that he's selling on average 125 copies of his article per day to Kindle owners - I'm guessing 50% market penetration, which would represent 7500 Kindles per month.

Repeat buyers will eventually be a factor, since you can share each download with up to 6 devices. I'm in that category, with a 2nd Kindle arriving next week (my son's birthday).

I just noticed that new comments keep popping up ahead of my answers, probably because of the way this site validates comments. So my apologies for seeming to answer questions out of order....

Richard - the robot is designed for indoor operation, and definitely isn't moisture-proof. However, it can handle varied terrain. Here's a short Quicktime clip (1.2MB) showing the robot climbing a 40-degree + incline - http://www.surveyor.com/images/srv1-trackbase1.mov

Jake - we're definitely looking at recharging station ideas, and we hope to eventually offer a contact-free charge pad. We've discussed this concept with Splashpower (http://www.splashpower.com ), but they're not yet ready to ship product.

Lettco - no lasers, but we did experiment with an AirSoft gun off a radio-controlled tank. It's definitely doable, though this isn't an option we plan to offer. If you're into that sort of thing, check out http://www.rctankcombat.com/tanks/

PSC - that's a cool idea. The average current draw for the robot is about 200mA @ 7.2VDC. I took a quick look in the Jameco catalog, and a 10" x 6" (250mm x 150mm) panel will produce that level of output. The robot itself is only 5" x 4", so there'd be some overhang, but it's probably manageable, or perhaps there are some higher efficiency modules around. The only other detail is that you'd really need a charge management circuit (Maxim makes suitable chips), and the solar module output would actually need to be in the 8-9VDC range in order to charge the 7.2V Li-ion pack.

Steve - the SRV-1 uses 802.15.4 rather than 802.11 for base-to-robot communication, so it won't connect to your existing Wi-fi. The IEEE 802.15.4 "Zigbee" standard was developed for relatively low bandwidth, low power sensor networks, and has the advantage of a very simple interface with minimal host software. We experimented with a variety of radio networks (including Bluetooth), before choosing this path. You can get more information about the Zigbee standard from http://www.zigbee.org - it's a very interesting piece of radio technology.

Thanks for the comments. We have 4 large dogs (one weighs 185 lbs), and the dogs tend to ignore the robots, generally running away if they get too close. The wires in the production units are actually a bit better tucked away than what's shown in that photo, but Fido (or in our case, Tank) could do some damage if he decided to smack the robot around, so we'd suggest some caution if dog-sitting is the primary application.

It seems that the content distribution companies believe that control of their format will somehow help them to maintain control of the distribution of their property. They only have to look back at the DVD encryption key debacle (my former company's software MPEG player was blamed for cracking of the encryption codes), to think that they have to do everything possible to lock things up for as long as possible, and somehow perceive that avoiding a common platform will somehow help them to preserve this security. From a bigger picture perspective, this is really narrow thinking, and the market for high definition content will take a LOT longer to develop, which essentially minimizes their return on investment, both with the new format, plus with sales of older DVD formats, since consumers aren't going to want to buy twice (or 3 times), but no doubt there's a much warmer, fuzzier feeling from taking the restrictive path.

Here's another example of ghetto surface mount - http://www.surveyor.com/cgi-bin/robot_journal.cgi/2006/03/07#020 - the skillet works great if you want to reflow an entire single-sided.