Timesheets for client billing makes some degree of sense (although I still hate filling them out).

Timesheets to measure productivity are completely pointless. Hours worked (or hours in the office) has almost no bearing on productivity. Measuring this is a far more complex process, although one obvious factor is whether a project was completed on time, on budget and met all agreed upon requirements.

I think flexitime for programmers is essential (so long as they're available for meetings, etc). I might spend 4 hours of the day and complete 2 days worth of work, but forcing me to work another 4 hours wouldn't necessary equate to even 4 more hours worth of work (and could lead to me burning out). A smart manager will recognise this. Fortunately, I currently work with managers like this.