The following was prepared to support articles dealing with land records for Pennsylvania, in conjunction with the "Old Chester" component of The Tapestry project. This article is based on information provided by Chartiers.com
That's the theory.
In practice, there are numerous instances where the formal process was not followed. Many settlers stopped the process at one or another points along the way, the land was never paid for, and a patent was not issued...at least immediately. Apparently the fact that they had settled the land was sufficient to protect it from claims by later buyers Chartiers.com. One of the results of this was that it might be many years before a patent was actually given for a property, long after the death of the original warrant holder. In many instances the person to whom the patent was finally issued had a different surname from the original owner, suggesting that perhaps the family was only prompted to complete the process when they decided to sell the land. Examples can be found where a warrant was granted prior to the Revolution, but the patent not issued in the 20th century. Examples can be found in the register where the patent was never issued at all.
The Pennsylvania Archives provide online access to many land records. It is relatively easy to find land records for a spercific individual, if you know when and where they might have acquired land. If the closest location you can get is "Pennsylvania", finding a land record will be a challenge, as most of the records are grouped by "County", and there's no surname index as such. However, if you've got a decent idea of where your ancestor lived in Pennsylvania, then you have a good chance of finding land records for them, assuming that they acquired land in the first place.
As an example, James Walker is thought to have settled in Pennsylvania in the 1730's, most likely in Lancaster County.
A word of warning. If you think your ancestor lived in the area of modern Cumberland County, but would have acquired his land by about 1740, there's no point in checking the Cumberland County lists, as Cumberland was not formed until 1751. Instead, you need to look at Lancaster County, the Cumberlands parent county. You will find that an understanding of the dates of County formation will simplify your search quite a bit.
Image:Pennsylvania Land Warrant example.jpg shows page 227 of the "W" warrant register for Lancaster County. Entry 67 shows that a James Walker obtained a warrant for 250 acres in Derry township, and in August of 1737, and secured the patent for this tract in January of 1738. Note that in many cases the corresponding patent is obtained many years after the warrant was issued, and often by someone other than the original warrant holder.
The warrant register contains much information of interest to genealogists. More information is available if the patent process was carried to completion. if you go to the above pointed example note that the last three columns include the entry "C 224 80". This specifies where a copy of the survey can be found. Go to COPIED SURVEYS, 1681-1912. This will give you a list of lettered volumes. Click the link "C-224", to go to the specific volume that contains James Walkers survey. From that page click the link "C-224-80" to go to James survey. See image:Example Survey Plot.jpg and image:Example Survey description.jpg to see example images taken from this survey. You may also find it useful to click the link that says "reverse" to find additional information that may have been recorded on the back of the survey page.