In recent years, there has been a considerable surge of interest within the analytical community in the development of closed-tube amplification and detection systems that permit the monitoring and detection of amplified nucleic acids in real-time. Such methodologies offer a number of advantages over alternative formats, where amplification and detection occur separately:
1) Potential for amplicon carry-over contamination is minimised - both amplification and detection systems are contained within a closed system so the amplified product can be analysed and disposed of without opening the reaction tubes.
2) Sample throughput is greatly increased - labour intensive post-amplification processing, such as gel electrophoresis and hybridisation, is not required.
3) The systems are highly compatible with automation technology.
The most established platforms for real-time PCR are the ABI Prism� 7700 Sequence Detection System and the Roche LightCycler.
ABI Prism� 7700 Sequence Detection System
This is a high throughput microtitre plate based system readily amenable to robotic automation and commonly used with TaqMan� probes (ABI). This utilises a conventional thermal cycler for target amplification and fluorescence-based homogeneous detection of PCR products. During each PCR cycle, the system monitors all wells using high speed, multi-colour fluorescence detection. Standard analytical runtime on this platform is 2-3 hours for 96 samples. However the high cost of both the equipment and consumables is prohibitive to many laboratories.
Click 
for a picture of the TaqMan
Roche LightCycler
This system combines a micro-volume fluorimeter with thermal cycling achieved by air conductivity, delivering accurate and rapid temperature control. This ability to rapidly alter temperatures permits the PCR procedure to be significantly shortened. A 30 cycle PCR can be completed within 10 minutes, compared to 2 to 3 hours using a conventional thermal cycler. However, the equipment is not designed for high throughput analysis as a maximum of 32 samples can be processed simultaneously.
Click for a Lightcycler picture