I decided to go with the TS200v and my particular model is the one with the Intel G1101/2.26GHz/2MB L2 celeron chip. Can I upgrade the same motherboard to a 3.60GHz 2.5GT/s DMI 4MB Cache Intel Core i5-680 Processor without causing trouble with the BIOS or other complications or compatibility issues?
The i5-680 is on the list of supported CPUs for the TS200v. With the i5-680 being only 73W, you shouldn't have any issues with cooling. The factory heatsink can take up to a 95W TDP processor.
One caveat: the new processor won't be covered under your factory warranty. The heatsink and system planar will remain covered as long as you don't damage them during the installation.
Helpful video instructions on the process, are available - you can follow the M91/M91p guide here: http://www.lenovoservicetraining.com/ion/M91p_Towe
(there currently isn't a video for the TS200v so the M91 is the closest system available)