It's been a while coming, but Lenovo's ThinkPad tablet has finally made its way to market. As expected, the line of Honeycomb slates is now available for order on the company's product page, with the 16GB, WiFi-only model priced at $500 and 3G-enabled versions going for $570 (32GB) and $670 (64GB). The 10.1-inch, NVIDIA Tegra 2-powered tablets are expected to begin shipping on August 29th, bu